xref: /external/chromium_org/gpu/command_buffer/service/gles2_cmd_decoder.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "gpu/command_buffer/service/gles2_cmd_decoder.h"

#include <stdio.h>

#include <algorithm>
#include <list>
#include <map>
#include <stack>
#include <string>
#include <vector>

#include "base/at_exit.h"
#include "base/bind.h"
#include "base/callback_helpers.h"
#include "base/command_line.h"
#include "base/debug/trace_event.h"
#include "base/debug/trace_event_synthetic_delay.h"
#include "base/memory/scoped_ptr.h"
#include "base/numerics/safe_math.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "build/build_config.h"
#define GLES2_GPU_SERVICE 1
#include "gpu/command_buffer/common/debug_marker_manager.h"
#include "gpu/command_buffer/common/gles2_cmd_format.h"
#include "gpu/command_buffer/common/gles2_cmd_utils.h"
#include "gpu/command_buffer/common/id_allocator.h"
#include "gpu/command_buffer/common/mailbox.h"
#include "gpu/command_buffer/service/async_pixel_transfer_delegate.h"
#include "gpu/command_buffer/service/async_pixel_transfer_manager.h"
#include "gpu/command_buffer/service/buffer_manager.h"
#include "gpu/command_buffer/service/cmd_buffer_engine.h"
#include "gpu/command_buffer/service/context_group.h"
#include "gpu/command_buffer/service/context_state.h"
#include "gpu/command_buffer/service/error_state.h"
#include "gpu/command_buffer/service/feature_info.h"
#include "gpu/command_buffer/service/framebuffer_manager.h"
#include "gpu/command_buffer/service/gl_utils.h"
#include "gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h"
#include "gpu/command_buffer/service/gles2_cmd_validation.h"
#include "gpu/command_buffer/service/gpu_state_tracer.h"
#include "gpu/command_buffer/service/gpu_switches.h"
#include "gpu/command_buffer/service/gpu_tracer.h"
#include "gpu/command_buffer/service/image_manager.h"
#include "gpu/command_buffer/service/mailbox_manager.h"
#include "gpu/command_buffer/service/memory_tracking.h"
#include "gpu/command_buffer/service/program_manager.h"
#include "gpu/command_buffer/service/query_manager.h"
#include "gpu/command_buffer/service/renderbuffer_manager.h"
#include "gpu/command_buffer/service/shader_manager.h"
#include "gpu/command_buffer/service/shader_translator.h"
#include "gpu/command_buffer/service/shader_translator_cache.h"
#include "gpu/command_buffer/service/texture_manager.h"
#include "gpu/command_buffer/service/vertex_array_manager.h"
#include "gpu/command_buffer/service/vertex_attrib_manager.h"
#include "third_party/smhasher/src/City.h"
#include "ui/gl/gl_bindings.h"
#include "ui/gl/gl_fence.h"
#include "ui/gl/gl_image.h"
#include "ui/gl/gl_implementation.h"
#include "ui/gl/gl_surface.h"

#if defined(OS_MACOSX)
#include <IOSurface/IOSurfaceAPI.h>
// Note that this must be included after gl_bindings.h to avoid conflicts.
#include <OpenGL/CGLIOSurface.h>
#endif

#if defined(OS_WIN)
#include "base/win/win_util.h"
#endif

namespace gpu {
namespace gles2 {

namespace {

static const char kOESDerivativeExtension[] = "GL_OES_standard_derivatives";
static const char kEXTFragDepthExtension[] = "GL_EXT_frag_depth";
static const char kEXTDrawBuffersExtension[] = "GL_EXT_draw_buffers";
static const char kEXTShaderTextureLodExtension[] = "GL_EXT_shader_texture_lod";

#if !defined(ANGLE_SH_VERSION) || ANGLE_SH_VERSION < 108
khronos_uint64_t CityHashForAngle(const char* name, unsigned int len) {
  return static_cast<khronos_uint64_t>(
      CityHash64(name, static_cast<size_t>(len)));
}
#endif

static bool PrecisionMeetsSpecForHighpFloat(GLint rangeMin,
                                            GLint rangeMax,
                                            GLint precision) {
  return (rangeMin >= 62) && (rangeMax >= 62) && (precision >= 16);
}

static void GetShaderPrecisionFormatImpl(GLenum shader_type,
                                         GLenum precision_type,
                                         GLint *range, GLint *precision) {
  switch (precision_type) {
    case GL_LOW_INT:
    case GL_MEDIUM_INT:
    case GL_HIGH_INT:
      // These values are for a 32-bit twos-complement integer format.
      range[0] = 31;
      range[1] = 30;
      *precision = 0;
      break;
    case GL_LOW_FLOAT:
    case GL_MEDIUM_FLOAT:
    case GL_HIGH_FLOAT:
      // These values are for an IEEE single-precision floating-point format.
      range[0] = 127;
      range[1] = 127;
      *precision = 23;
      break;
    default:
      NOTREACHED();
      break;
  }

  if (gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2 &&
      gfx::g_driver_gl.fn.glGetShaderPrecisionFormatFn) {
    // This function is sometimes defined even though it's really just
    // a stub, so we need to set range and precision as if it weren't
    // defined before calling it.
    // On Mac OS with some GPUs, calling this generates a
    // GL_INVALID_OPERATION error. Avoid calling it on non-GLES2
    // platforms.
    glGetShaderPrecisionFormat(shader_type, precision_type,
                               range, precision);

    // TODO(brianderson): Make the following official workarounds.

    // Some drivers have bugs where they report the ranges as a negative number.
    // Taking the absolute value here shouldn't hurt because negative numbers
    // aren't expected anyway.
    range[0] = abs(range[0]);
    range[1] = abs(range[1]);

    // If the driver reports a precision for highp float that isn't actually
    // highp, don't pretend like it's supported because shader compilation will
    // fail anyway.
    if (precision_type == GL_HIGH_FLOAT &&
        !PrecisionMeetsSpecForHighpFloat(range[0], range[1], *precision)) {
      range[0] = 0;
      range[1] = 0;
      *precision = 0;
    }
  }
}

}  // namespace

class GLES2DecoderImpl;

// Local versions of the SET_GL_ERROR macros
#define LOCAL_SET_GL_ERROR(error, function_name, msg) \
    ERRORSTATE_SET_GL_ERROR(state_.GetErrorState(), error, function_name, msg)
#define LOCAL_SET_GL_ERROR_INVALID_ENUM(function_name, value, label) \
    ERRORSTATE_SET_GL_ERROR_INVALID_ENUM(state_.GetErrorState(), \
                                         function_name, value, label)
#define LOCAL_SET_GL_ERROR_INVALID_PARAM(error, function_name, pname) \
    ERRORSTATE_SET_GL_ERROR_INVALID_PARAM(state_.GetErrorState(), error, \
                                          function_name, pname)
#define LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER(function_name) \
    ERRORSTATE_COPY_REAL_GL_ERRORS_TO_WRAPPER(state_.GetErrorState(), \
                                              function_name)
#define LOCAL_PEEK_GL_ERROR(function_name) \
    ERRORSTATE_PEEK_GL_ERROR(state_.GetErrorState(), function_name)
#define LOCAL_CLEAR_REAL_GL_ERRORS(function_name) \
    ERRORSTATE_CLEAR_REAL_GL_ERRORS(state_.GetErrorState(), function_name)
#define LOCAL_PERFORMANCE_WARNING(msg) \
    PerformanceWarning(__FILE__, __LINE__, msg)
#define LOCAL_RENDER_WARNING(msg) \
    RenderWarning(__FILE__, __LINE__, msg)

// Check that certain assumptions the code makes are true. There are places in
// the code where shared memory is passed direclty to GL. Example, glUniformiv,
// glShaderSource. The command buffer code assumes GLint and GLsizei (and maybe
// a few others) are 32bits. If they are not 32bits the code will have to change
// to call those GL functions with service side memory and then copy the results
// to shared memory, converting the sizes.
COMPILE_ASSERT(sizeof(GLint) == sizeof(uint32),  // NOLINT
               GLint_not_same_size_as_uint32);
COMPILE_ASSERT(sizeof(GLsizei) == sizeof(uint32),  // NOLINT
               GLint_not_same_size_as_uint32);
COMPILE_ASSERT(sizeof(GLfloat) == sizeof(float),  // NOLINT
               GLfloat_not_same_size_as_float);

// TODO(kbr): the use of this anonymous namespace core dumps the
// linker on Mac OS X 10.6 when the symbol ordering file is used
// namespace {

// Returns the address of the first byte after a struct.
template <typename T>
const void* AddressAfterStruct(const T& pod) {
  return reinterpret_cast<const uint8*>(&pod) + sizeof(pod);
}

// Returns the address of the frst byte after the struct or NULL if size >
// immediate_data_size.
template <typename RETURN_TYPE, typename COMMAND_TYPE>
RETURN_TYPE GetImmediateDataAs(const COMMAND_TYPE& pod,
                               uint32 size,
                               uint32 immediate_data_size) {
  return (size <= immediate_data_size) ?
      static_cast<RETURN_TYPE>(const_cast<void*>(AddressAfterStruct(pod))) :
      NULL;
}

// Computes the data size for certain gl commands like glUniform.
bool ComputeDataSize(
    GLuint count,
    size_t size,
    unsigned int elements_per_unit,
    uint32* dst) {
  uint32 value;
  if (!SafeMultiplyUint32(count, size, &value)) {
    return false;
  }
  if (!SafeMultiplyUint32(value, elements_per_unit, &value)) {
    return false;
  }
  *dst = value;
  return true;
}

// A struct to hold info about each command.
struct CommandInfo {
  uint8 arg_flags;   // How to handle the arguments for this command
  uint8 cmd_flags;   // How to handle this command
  uint16 arg_count;  // How many arguments are expected for this command.
};

//     cmds::name::cmd_flags,
// A table of CommandInfo for all the commands.
const CommandInfo g_command_info[] = {
  #define GLES2_CMD_OP(name) {                                             \
    cmds::name::kArgFlags,                                                 \
    cmds::name::cmd_flags,                                                 \
    sizeof(cmds::name) / sizeof(CommandBufferEntry) - 1, },  /* NOLINT */

  GLES2_COMMAND_LIST(GLES2_CMD_OP)

  #undef GLES2_CMD_OP
};

// Return true if a character belongs to the ASCII subset as defined in
// GLSL ES 1.0 spec section 3.1.
static bool CharacterIsValidForGLES(unsigned char c) {
  // Printing characters are valid except " $ ` @ \ ' DEL.
  if (c >= 32 && c <= 126 &&
      c != '"' &&
      c != '$' &&
      c != '`' &&
      c != '@' &&
      c != '\\' &&
      c != '\'') {
    return true;
  }
  // Horizontal tab, line feed, vertical tab, form feed, carriage return
  // are also valid.
  if (c >= 9 && c <= 13) {
    return true;
  }

  return false;
}

static bool StringIsValidForGLES(const char* str) {
  for (; *str; ++str) {
    if (!CharacterIsValidForGLES(*str)) {
      return false;
    }
  }
  return true;
}

// This class prevents any GL errors that occur when it is in scope from
// being reported to the client.
class ScopedGLErrorSuppressor {
 public:
  explicit ScopedGLErrorSuppressor(
      const char* function_name, ErrorState* error_state);
  ~ScopedGLErrorSuppressor();
 private:
  const char* function_name_;
  ErrorState* error_state_;
  DISALLOW_COPY_AND_ASSIGN(ScopedGLErrorSuppressor);
};

// Temporarily changes a decoder's bound texture and restore it when this
// object goes out of scope. Also temporarily switches to using active texture
// unit zero in case the client has changed that to something invalid.
class ScopedTextureBinder {
 public:
  explicit ScopedTextureBinder(ContextState* state, GLuint id, GLenum target);
  ~ScopedTextureBinder();

 private:
  ContextState* state_;
  GLenum target_;
  DISALLOW_COPY_AND_ASSIGN(ScopedTextureBinder);
};

// Temporarily changes a decoder's bound render buffer and restore it when this
// object goes out of scope.
class ScopedRenderBufferBinder {
 public:
  explicit ScopedRenderBufferBinder(ContextState* state, GLuint id);
  ~ScopedRenderBufferBinder();

 private:
  ContextState* state_;
  DISALLOW_COPY_AND_ASSIGN(ScopedRenderBufferBinder);
};

// Temporarily changes a decoder's bound frame buffer and restore it when this
// object goes out of scope.
class ScopedFrameBufferBinder {
 public:
  explicit ScopedFrameBufferBinder(GLES2DecoderImpl* decoder, GLuint id);
  ~ScopedFrameBufferBinder();

 private:
  GLES2DecoderImpl* decoder_;
  DISALLOW_COPY_AND_ASSIGN(ScopedFrameBufferBinder);
};

// Temporarily changes a decoder's bound frame buffer to a resolved version of
// the multisampled offscreen render buffer if that buffer is multisampled, and,
// if it is bound or enforce_internal_framebuffer is true. If internal is
// true, the resolved framebuffer is not visible to the parent.
class ScopedResolvedFrameBufferBinder {
 public:
  explicit ScopedResolvedFrameBufferBinder(GLES2DecoderImpl* decoder,
                                           bool enforce_internal_framebuffer,
                                           bool internal);
  ~ScopedResolvedFrameBufferBinder();

 private:
  GLES2DecoderImpl* decoder_;
  bool resolve_and_bind_;
  DISALLOW_COPY_AND_ASSIGN(ScopedResolvedFrameBufferBinder);
};

class ScopedModifyPixels {
 public:
  explicit ScopedModifyPixels(TextureRef* ref);
  ~ScopedModifyPixels();

 private:
  TextureRef* ref_;
};

ScopedModifyPixels::ScopedModifyPixels(TextureRef* ref) : ref_(ref) {
  if (ref_)
    ref_->texture()->OnWillModifyPixels();
}

ScopedModifyPixels::~ScopedModifyPixels() {
  if (ref_)
    ref_->texture()->OnDidModifyPixels();
}

class ScopedRenderTo {
 public:
  explicit ScopedRenderTo(Framebuffer* framebuffer);
  ~ScopedRenderTo();

 private:
  const Framebuffer* framebuffer_;
};

ScopedRenderTo::ScopedRenderTo(Framebuffer* framebuffer)
    : framebuffer_(framebuffer) {
  if (framebuffer)
    framebuffer_->OnWillRenderTo();
}

ScopedRenderTo::~ScopedRenderTo() {
  if (framebuffer_)
    framebuffer_->OnDidRenderTo();
}

// Encapsulates an OpenGL texture.
class BackTexture {
 public:
  explicit BackTexture(MemoryTracker* memory_tracker, ContextState* state);
  ~BackTexture();

  // Create a new render texture.
  void Create();

  // Set the initial size and format of a render texture or resize it.
  bool AllocateStorage(const gfx::Size& size, GLenum format, bool zero);

  // Copy the contents of the currently bound frame buffer.
  void Copy(const gfx::Size& size, GLenum format);

  // Destroy the render texture. This must be explicitly called before
  // destroying this object.
  void Destroy();

  // Invalidate the texture. This can be used when a context is lost and it is
  // not possible to make it current in order to free the resource.
  void Invalidate();

  GLuint id() const {
    return id_;
  }

  gfx::Size size() const {
    return size_;
  }

 private:
  MemoryTypeTracker memory_tracker_;
  ContextState* state_;
  size_t bytes_allocated_;
  GLuint id_;
  gfx::Size size_;
  DISALLOW_COPY_AND_ASSIGN(BackTexture);
};

// Encapsulates an OpenGL render buffer of any format.
class BackRenderbuffer {
 public:
  explicit BackRenderbuffer(
      RenderbufferManager* renderbuffer_manager,
      MemoryTracker* memory_tracker,
      ContextState* state);
  ~BackRenderbuffer();

  // Create a new render buffer.
  void Create();

  // Set the initial size and format of a render buffer or resize it.
  bool AllocateStorage(const FeatureInfo* feature_info,
                       const gfx::Size& size,
                       GLenum format,
                       GLsizei samples);

  // Destroy the render buffer. This must be explicitly called before destroying
  // this object.
  void Destroy();

  // Invalidate the render buffer. This can be used when a context is lost and
  // it is not possible to make it current in order to free the resource.
  void Invalidate();

  GLuint id() const {
    return id_;
  }

 private:
  RenderbufferManager* renderbuffer_manager_;
  MemoryTypeTracker memory_tracker_;
  ContextState* state_;
  size_t bytes_allocated_;
  GLuint id_;
  DISALLOW_COPY_AND_ASSIGN(BackRenderbuffer);
};

// Encapsulates an OpenGL frame buffer.
class BackFramebuffer {
 public:
  explicit BackFramebuffer(GLES2DecoderImpl* decoder);
  ~BackFramebuffer();

  // Create a new frame buffer.
  void Create();

  // Attach a color render buffer to a frame buffer.
  void AttachRenderTexture(BackTexture* texture);

  // Attach a render buffer to a frame buffer. Note that this unbinds any
  // currently bound frame buffer.
  void AttachRenderBuffer(GLenum target, BackRenderbuffer* render_buffer);

  // Destroy the frame buffer. This must be explicitly called before destroying
  // this object.
  void Destroy();

  // Invalidate the frame buffer. This can be used when a context is lost and it
  // is not possible to make it current in order to free the resource.
  void Invalidate();

  // See glCheckFramebufferStatusEXT.
  GLenum CheckStatus();

  GLuint id() const {
    return id_;
  }

 private:
  GLES2DecoderImpl* decoder_;
  GLuint id_;
  DISALLOW_COPY_AND_ASSIGN(BackFramebuffer);
};

struct FenceCallback {
  explicit FenceCallback()
      : fence(gfx::GLFence::Create()) {
    DCHECK(fence);
  }
  std::vector<base::Closure> callbacks;
  scoped_ptr<gfx::GLFence> fence;
};

class AsyncUploadTokenCompletionObserver
    : public AsyncPixelTransferCompletionObserver {
 public:
  explicit AsyncUploadTokenCompletionObserver(uint32 async_upload_token)
      : async_upload_token_(async_upload_token) {
  }

  virtual void DidComplete(const AsyncMemoryParams& mem_params) OVERRIDE {
    DCHECK(mem_params.buffer());
    void* data = mem_params.GetDataAddress();
    AsyncUploadSync* sync = static_cast<AsyncUploadSync*>(data);
    sync->SetAsyncUploadToken(async_upload_token_);
  }

 private:
  virtual ~AsyncUploadTokenCompletionObserver() {
  }

  uint32 async_upload_token_;

  DISALLOW_COPY_AND_ASSIGN(AsyncUploadTokenCompletionObserver);
};

// }  // anonymous namespace.

bool GLES2Decoder::GetServiceTextureId(uint32 client_texture_id,
                                       uint32* service_texture_id) {
  return false;
}

GLES2Decoder::GLES2Decoder()
    : initialized_(false),
      debug_(false),
      log_commands_(false) {
}

GLES2Decoder::~GLES2Decoder() {
}

void GLES2Decoder::BeginDecoding() {}

void GLES2Decoder::EndDecoding() {}

// This class implements GLES2Decoder so we don't have to expose all the GLES2
// cmd stuff to outside this class.
class GLES2DecoderImpl : public GLES2Decoder,
                         public FramebufferManager::TextureDetachObserver,
                         public ErrorStateClient {
 public:
  explicit GLES2DecoderImpl(ContextGroup* group);
  virtual ~GLES2DecoderImpl();

  // Overridden from AsyncAPIInterface.
  virtual Error DoCommand(unsigned int command,
                          unsigned int arg_count,
                          const void* args) OVERRIDE;

  // Overridden from AsyncAPIInterface.
  virtual const char* GetCommandName(unsigned int command_id) const OVERRIDE;

  // Overridden from GLES2Decoder.
  virtual bool Initialize(const scoped_refptr<gfx::GLSurface>& surface,
                          const scoped_refptr<gfx::GLContext>& context,
                          bool offscreen,
                          const gfx::Size& size,
                          const DisallowedFeatures& disallowed_features,
                          const std::vector<int32>& attribs) OVERRIDE;
  virtual void Destroy(bool have_context) OVERRIDE;
  virtual void SetSurface(
      const scoped_refptr<gfx::GLSurface>& surface) OVERRIDE;
  virtual void ProduceFrontBuffer(const Mailbox& mailbox) OVERRIDE;
  virtual bool ResizeOffscreenFrameBuffer(const gfx::Size& size) OVERRIDE;
  void UpdateParentTextureInfo();
  virtual bool MakeCurrent() OVERRIDE;
  virtual GLES2Util* GetGLES2Util() OVERRIDE { return &util_; }
  virtual gfx::GLContext* GetGLContext() OVERRIDE { return context_.get(); }
  virtual ContextGroup* GetContextGroup() OVERRIDE { return group_.get(); }
  virtual Capabilities GetCapabilities() OVERRIDE;
  virtual void RestoreState(const ContextState* prev_state) const OVERRIDE;

  virtual void RestoreActiveTexture() const OVERRIDE {
    state_.RestoreActiveTexture();
  }
  virtual void RestoreAllTextureUnitBindings(
      const ContextState* prev_state) const OVERRIDE {
    state_.RestoreAllTextureUnitBindings(prev_state);
  }
  virtual void RestoreActiveTextureUnitBinding(
      unsigned int target) const OVERRIDE {
    state_.RestoreActiveTextureUnitBinding(target);
  }
  virtual void RestoreBufferBindings() const OVERRIDE {
    state_.RestoreBufferBindings();
  }
  virtual void RestoreGlobalState() const OVERRIDE {
    state_.RestoreGlobalState(NULL);
  }
  virtual void RestoreProgramBindings() const OVERRIDE {
    state_.RestoreProgramBindings();
  }
  virtual void RestoreTextureUnitBindings(unsigned unit) const OVERRIDE {
    state_.RestoreTextureUnitBindings(unit, NULL);
  }
  virtual void RestoreFramebufferBindings() const OVERRIDE;
  virtual void RestoreTextureState(unsigned service_id) const OVERRIDE;

  virtual void ClearAllAttributes() const OVERRIDE;
  virtual void RestoreAllAttributes() const OVERRIDE;

  virtual QueryManager* GetQueryManager() OVERRIDE {
    return query_manager_.get();
  }
  virtual VertexArrayManager* GetVertexArrayManager() OVERRIDE {
    return vertex_array_manager_.get();
  }
  virtual bool ProcessPendingQueries() OVERRIDE;
  virtual bool HasMoreIdleWork() OVERRIDE;
  virtual void PerformIdleWork() OVERRIDE;

  virtual void WaitForReadPixels(base::Closure callback) OVERRIDE;

  virtual void SetResizeCallback(
      const base::Callback<void(gfx::Size, float)>& callback) OVERRIDE;

  virtual Logger* GetLogger() OVERRIDE;

  virtual void BeginDecoding() OVERRIDE;
  virtual void EndDecoding() OVERRIDE;

  virtual ErrorState* GetErrorState() OVERRIDE;
  virtual const ContextState* GetContextState() OVERRIDE { return &state_; }

  virtual void SetShaderCacheCallback(
      const ShaderCacheCallback& callback) OVERRIDE;
  virtual void SetWaitSyncPointCallback(
      const WaitSyncPointCallback& callback) OVERRIDE;

  virtual AsyncPixelTransferManager*
      GetAsyncPixelTransferManager() OVERRIDE;
  virtual void ResetAsyncPixelTransferManagerForTest() OVERRIDE;
  virtual void SetAsyncPixelTransferManagerForTest(
      AsyncPixelTransferManager* manager) OVERRIDE;
  virtual void SetIgnoreCachedStateForTest(bool ignore) OVERRIDE;
  void ProcessFinishedAsyncTransfers();

  virtual bool GetServiceTextureId(uint32 client_texture_id,
                                   uint32* service_texture_id) OVERRIDE;

  virtual uint32 GetTextureUploadCount() OVERRIDE;
  virtual base::TimeDelta GetTotalTextureUploadTime() OVERRIDE;
  virtual base::TimeDelta GetTotalProcessingCommandsTime() OVERRIDE;
  virtual void AddProcessingCommandsTime(base::TimeDelta) OVERRIDE;

  // Restores the current state to the user's settings.
  void RestoreCurrentFramebufferBindings();

  // Sets DEPTH_TEST, STENCIL_TEST and color mask for the current framebuffer.
  void ApplyDirtyState();

  // These check the state of the currently bound framebuffer or the
  // backbuffer if no framebuffer is bound.
  // If all_draw_buffers is false, only check with COLOR_ATTACHMENT0, otherwise
  // check with all attached and enabled color attachments.
  bool BoundFramebufferHasColorAttachmentWithAlpha(bool all_draw_buffers);
  bool BoundFramebufferHasDepthAttachment();
  bool BoundFramebufferHasStencilAttachment();

  virtual error::ContextLostReason GetContextLostReason() OVERRIDE;

  // Overridden from FramebufferManager::TextureDetachObserver:
  virtual void OnTextureRefDetachedFromFramebuffer(
      TextureRef* texture) OVERRIDE;

  // Overriden from ErrorStateClient.
  virtual void OnOutOfMemoryError() OVERRIDE;

  // Helpers to facilitate calling into compatible extensions.
  static void RenderbufferStorageMultisampleHelper(
      const FeatureInfo* feature_info,
      GLenum target,
      GLsizei samples,
      GLenum internal_format,
      GLsizei width,
      GLsizei height);

  void BlitFramebufferHelper(GLint srcX0,
                             GLint srcY0,
                             GLint srcX1,
                             GLint srcY1,
                             GLint dstX0,
                             GLint dstY0,
                             GLint dstX1,
                             GLint dstY1,
                             GLbitfield mask,
                             GLenum filter);

 private:
  friend class ScopedFrameBufferBinder;
  friend class ScopedResolvedFrameBufferBinder;
  friend class BackFramebuffer;

  // Initialize or re-initialize the shader translator.
  bool InitializeShaderTranslator();

  void UpdateCapabilities();

  // Helpers for the glGen and glDelete functions.
  bool GenTexturesHelper(GLsizei n, const GLuint* client_ids);
  void DeleteTexturesHelper(GLsizei n, const GLuint* client_ids);
  bool GenBuffersHelper(GLsizei n, const GLuint* client_ids);
  void DeleteBuffersHelper(GLsizei n, const GLuint* client_ids);
  bool GenFramebuffersHelper(GLsizei n, const GLuint* client_ids);
  void DeleteFramebuffersHelper(GLsizei n, const GLuint* client_ids);
  bool GenRenderbuffersHelper(GLsizei n, const GLuint* client_ids);
  void DeleteRenderbuffersHelper(GLsizei n, const GLuint* client_ids);
  bool GenQueriesEXTHelper(GLsizei n, const GLuint* client_ids);
  void DeleteQueriesEXTHelper(GLsizei n, const GLuint* client_ids);
  bool GenVertexArraysOESHelper(GLsizei n, const GLuint* client_ids);
  void DeleteVertexArraysOESHelper(GLsizei n, const GLuint* client_ids);

  // Helper for async upload token completion notification callback.
  base::Closure AsyncUploadTokenCompletionClosure(uint32 async_upload_token,
                                                  uint32 sync_data_shm_id,
                                                  uint32 sync_data_shm_offset);



  // Workarounds
  void OnFboChanged() const;
  void OnUseFramebuffer() const;

  // TODO(gman): Cache these pointers?
  BufferManager* buffer_manager() {
    return group_->buffer_manager();
  }

  RenderbufferManager* renderbuffer_manager() {
    return group_->renderbuffer_manager();
  }

  FramebufferManager* framebuffer_manager() {
    return group_->framebuffer_manager();
  }

  ProgramManager* program_manager() {
    return group_->program_manager();
  }

  ShaderManager* shader_manager() {
    return group_->shader_manager();
  }

  ShaderTranslatorCache* shader_translator_cache() {
    return group_->shader_translator_cache();
  }

  const TextureManager* texture_manager() const {
    return group_->texture_manager();
  }

  TextureManager* texture_manager() {
    return group_->texture_manager();
  }

  MailboxManager* mailbox_manager() {
    return group_->mailbox_manager();
  }

  ImageManager* image_manager() {
    return group_->image_manager();
  }

  VertexArrayManager* vertex_array_manager() {
    return vertex_array_manager_.get();
  }

  MemoryTracker* memory_tracker() {
    return group_->memory_tracker();
  }

  bool EnsureGPUMemoryAvailable(size_t estimated_size) {
    MemoryTracker* tracker = memory_tracker();
    if (tracker) {
      return tracker->EnsureGPUMemoryAvailable(estimated_size);
    }
    return true;
  }

  bool IsOffscreenBufferMultisampled() const {
    return offscreen_target_samples_ > 1;
  }

  // Creates a Texture for the given texture.
  TextureRef* CreateTexture(
      GLuint client_id, GLuint service_id) {
    return texture_manager()->CreateTexture(client_id, service_id);
  }

  // Gets the texture info for the given texture. Returns NULL if none exists.
  TextureRef* GetTexture(GLuint client_id) const {
    return texture_manager()->GetTexture(client_id);
  }

  // Deletes the texture info for the given texture.
  void RemoveTexture(GLuint client_id) {
    texture_manager()->RemoveTexture(client_id);
  }

  // Get the size (in pixels) of the currently bound frame buffer (either FBO
  // or regular back buffer).
  gfx::Size GetBoundReadFrameBufferSize();

  // Get the format of the currently bound frame buffer (either FBO or regular
  // back buffer)
  GLenum GetBoundReadFrameBufferTextureType();
  GLenum GetBoundReadFrameBufferInternalFormat();
  GLenum GetBoundDrawFrameBufferInternalFormat();

  // Wrapper for CompressedTexImage2D commands.
  error::Error DoCompressedTexImage2D(
      GLenum target,
      GLint level,
      GLenum internal_format,
      GLsizei width,
      GLsizei height,
      GLint border,
      GLsizei image_size,
      const void* data);

  // Wrapper for CompressedTexSubImage2D.
  void DoCompressedTexSubImage2D(
      GLenum target,
      GLint level,
      GLint xoffset,
      GLint yoffset,
      GLsizei width,
      GLsizei height,
      GLenum format,
      GLsizei imageSize,
      const void * data);

  // Wrapper for CopyTexImage2D.
  void DoCopyTexImage2D(
      GLenum target,
      GLint level,
      GLenum internal_format,
      GLint x,
      GLint y,
      GLsizei width,
      GLsizei height,
      GLint border);

  // Wrapper for SwapBuffers.
  void DoSwapBuffers();

  // Wrapper for CopyTexSubImage2D.
  void DoCopyTexSubImage2D(
      GLenum target,
      GLint level,
      GLint xoffset,
      GLint yoffset,
      GLint x,
      GLint y,
      GLsizei width,
      GLsizei height);

  // Validation for TexSubImage2D.
  bool ValidateTexSubImage2D(
      error::Error* error,
      const char* function_name,
      GLenum target,
      GLint level,
      GLint xoffset,
      GLint yoffset,
      GLsizei width,
      GLsizei height,
      GLenum format,
      GLenum type,
      const void * data);

  // Wrapper for TexSubImage2D.
  error::Error DoTexSubImage2D(
      GLenum target,
      GLint level,
      GLint xoffset,
      GLint yoffset,
      GLsizei width,
      GLsizei height,
      GLenum format,
      GLenum type,
      const void * data);

  // Extra validation for async tex(Sub)Image2D.
  bool ValidateAsyncTransfer(
      const char* function_name,
      TextureRef* texture_ref,
      GLenum target,
      GLint level,
      const void * data);

  // Wrapper for TexImageIOSurface2DCHROMIUM.
  void DoTexImageIOSurface2DCHROMIUM(
      GLenum target,
      GLsizei width,
      GLsizei height,
      GLuint io_surface_id,
      GLuint plane);

  void DoCopyTextureCHROMIUM(
      GLenum target,
      GLuint source_id,
      GLuint target_id,
      GLint level,
      GLenum internal_format,
      GLenum dest_type);

  // Wrapper for TexStorage2DEXT.
  void DoTexStorage2DEXT(
      GLenum target,
      GLint levels,
      GLenum internal_format,
      GLsizei width,
      GLsizei height);

  void DoProduceTextureCHROMIUM(GLenum target, const GLbyte* key);
  void DoProduceTextureDirectCHROMIUM(GLuint texture, GLenum target,
      const GLbyte* key);
  void ProduceTextureRef(std::string func_name, TextureRef* texture_ref,
      GLenum target, const GLbyte* data);

  void DoConsumeTextureCHROMIUM(GLenum target, const GLbyte* key);
  void DoCreateAndConsumeTextureCHROMIUM(GLenum target, const GLbyte* key,
    GLuint client_id);

  void DoBindTexImage2DCHROMIUM(
      GLenum target,
      GLint image_id);
  void DoReleaseTexImage2DCHROMIUM(
      GLenum target,
      GLint image_id);

  void DoTraceEndCHROMIUM(void);

  void DoDrawBuffersEXT(GLsizei count, const GLenum* bufs);

  void DoLoseContextCHROMIUM(GLenum current, GLenum other);

  // Creates a Program for the given program.
  Program* CreateProgram(
      GLuint client_id, GLuint service_id) {
    return program_manager()->CreateProgram(client_id, service_id);
  }

  // Gets the program info for the given program. Returns NULL if none exists.
  Program* GetProgram(GLuint client_id) {
    return program_manager()->GetProgram(client_id);
  }

#if defined(NDEBUG)
  void LogClientServiceMapping(
      const char* /* function_name */,
      GLuint /* client_id */,
      GLuint /* service_id */) {
  }
  template<typename T>
  void LogClientServiceForInfo(
      T* /* info */, GLuint /* client_id */, const char* /* function_name */) {
  }
#else
  void LogClientServiceMapping(
      const char* function_name, GLuint client_id, GLuint service_id) {
    if (service_logging_) {
      VLOG(1) << "[" << logger_.GetLogPrefix() << "] " << function_name
              << ": client_id = " << client_id
              << ", service_id = " << service_id;
    }
  }
  template<typename T>
  void LogClientServiceForInfo(
      T* info, GLuint client_id, const char* function_name) {
    if (info) {
      LogClientServiceMapping(function_name, client_id, info->service_id());
    }
  }
#endif

  // Gets the program info for the given program. If it's not a program
  // generates a GL error. Returns NULL if not program.
  Program* GetProgramInfoNotShader(
      GLuint client_id, const char* function_name) {
    Program* program = GetProgram(client_id);
    if (!program) {
      if (GetShader(client_id)) {
        LOCAL_SET_GL_ERROR(
            GL_INVALID_OPERATION, function_name, "shader passed for program");
      } else {
        LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "unknown program");
      }
    }
    LogClientServiceForInfo(program, client_id, function_name);
    return program;
  }


  // Creates a Shader for the given shader.
  Shader* CreateShader(
      GLuint client_id,
      GLuint service_id,
      GLenum shader_type) {
    return shader_manager()->CreateShader(
        client_id, service_id, shader_type);
  }

  // Gets the shader info for the given shader. Returns NULL if none exists.
  Shader* GetShader(GLuint client_id) {
    return shader_manager()->GetShader(client_id);
  }

  // Gets the shader info for the given shader. If it's not a shader generates a
  // GL error. Returns NULL if not shader.
  Shader* GetShaderInfoNotProgram(
      GLuint client_id, const char* function_name) {
    Shader* shader = GetShader(client_id);
    if (!shader) {
      if (GetProgram(client_id)) {
        LOCAL_SET_GL_ERROR(
            GL_INVALID_OPERATION, function_name, "program passed for shader");
      } else {
        LOCAL_SET_GL_ERROR(
            GL_INVALID_VALUE, function_name, "unknown shader");
      }
    }
    LogClientServiceForInfo(shader, client_id, function_name);
    return shader;
  }

  // Creates a buffer info for the given buffer.
  void CreateBuffer(GLuint client_id, GLuint service_id) {
    return buffer_manager()->CreateBuffer(client_id, service_id);
  }

  // Gets the buffer info for the given buffer.
  Buffer* GetBuffer(GLuint client_id) {
    Buffer* buffer = buffer_manager()->GetBuffer(client_id);
    return buffer;
  }

  // Removes any buffers in the VertexAtrribInfos and BufferInfos. This is used
  // on glDeleteBuffers so we can make sure the user does not try to render
  // with deleted buffers.
  void RemoveBuffer(GLuint client_id);

  // Creates a framebuffer info for the given framebuffer.
  void CreateFramebuffer(GLuint client_id, GLuint service_id) {
    return framebuffer_manager()->CreateFramebuffer(client_id, service_id);
  }

  // Gets the framebuffer info for the given framebuffer.
  Framebuffer* GetFramebuffer(GLuint client_id) {
    return framebuffer_manager()->GetFramebuffer(client_id);
  }

  // Removes the framebuffer info for the given framebuffer.
  void RemoveFramebuffer(GLuint client_id) {
    framebuffer_manager()->RemoveFramebuffer(client_id);
  }

  // Creates a renderbuffer info for the given renderbuffer.
  void CreateRenderbuffer(GLuint client_id, GLuint service_id) {
    return renderbuffer_manager()->CreateRenderbuffer(
        client_id, service_id);
  }

  // Gets the renderbuffer info for the given renderbuffer.
  Renderbuffer* GetRenderbuffer(GLuint client_id) {
    return renderbuffer_manager()->GetRenderbuffer(client_id);
  }

  // Removes the renderbuffer info for the given renderbuffer.
  void RemoveRenderbuffer(GLuint client_id) {
    renderbuffer_manager()->RemoveRenderbuffer(client_id);
  }

  // Gets the vertex attrib manager for the given vertex array.
  VertexAttribManager* GetVertexAttribManager(GLuint client_id) {
    VertexAttribManager* info =
        vertex_array_manager()->GetVertexAttribManager(client_id);
    return info;
  }

  // Removes the vertex attrib manager for the given vertex array.
  void RemoveVertexAttribManager(GLuint client_id) {
    vertex_array_manager()->RemoveVertexAttribManager(client_id);
  }

  // Creates a vertex attrib manager for the given vertex array.
  scoped_refptr<VertexAttribManager> CreateVertexAttribManager(
      GLuint client_id,
      GLuint service_id,
      bool client_visible) {
    return vertex_array_manager()->CreateVertexAttribManager(
        client_id, service_id, group_->max_vertex_attribs(), client_visible);
  }

  void DoBindAttribLocation(GLuint client_id, GLuint index, const char* name);
  void DoBindUniformLocationCHROMIUM(
      GLuint client_id, GLint location, const char* name);

  error::Error GetAttribLocationHelper(
    GLuint client_id, uint32 location_shm_id, uint32 location_shm_offset,
    const std::string& name_str);

  error::Error GetUniformLocationHelper(
    GLuint client_id, uint32 location_shm_id, uint32 location_shm_offset,
    const std::string& name_str);

  // Helper for glShaderSource.
  error::Error ShaderSourceHelper(
      GLuint client_id, const char* data, uint32 data_size);

  // Clear any textures used by the current program.
  bool ClearUnclearedTextures();

  // Clears any uncleared attachments attached to the given frame buffer.
  // Returns false if there was a generated GL error.
  void ClearUnclearedAttachments(GLenum target, Framebuffer* framebuffer);

  // overridden from GLES2Decoder
  virtual bool ClearLevel(unsigned service_id,
                          unsigned bind_target,
                          unsigned target,
                          int level,
                          unsigned internal_format,
                          unsigned format,
                          unsigned type,
                          int width,
                          int height,
                          bool is_texture_immutable) OVERRIDE;

  // Restore all GL state that affects clearing.
  void RestoreClearState();

  // Remembers the state of some capabilities.
  // Returns: true if glEnable/glDisable should actually be called.
  bool SetCapabilityState(GLenum cap, bool enabled);

  // Check that the currently bound framebuffers are valid.
  // Generates GL error if not.
  bool CheckBoundFramebuffersValid(const char* func_name);

  // Check if a framebuffer meets our requirements.
  bool CheckFramebufferValid(
      Framebuffer* framebuffer,
      GLenum target,
      const char* func_name);

  // Checks if the current program exists and is valid. If not generates the
  // appropriate GL error.  Returns true if the current program is in a usable
  // state.
  bool CheckCurrentProgram(const char* function_name);

  // Checks if the current program exists and is valid and that location is not
  // -1. If the current program is not valid generates the appropriate GL
  // error. Returns true if the current program is in a usable state and
  // location is not -1.
  bool CheckCurrentProgramForUniform(GLint location, const char* function_name);

  // Gets the type of a uniform for a location in the current program. Sets GL
  // errors if the current program is not valid. Returns true if the current
  // program is valid and the location exists. Adjusts count so it
  // does not overflow the uniform.
  bool PrepForSetUniformByLocation(GLint fake_location,
                                   const char* function_name,
                                   Program::UniformApiType api_type,
                                   GLint* real_location,
                                   GLenum* type,
                                   GLsizei* count);

  // Gets the service id for any simulated backbuffer fbo.
  GLuint GetBackbufferServiceId() const;

  // Helper for glGetBooleanv, glGetFloatv and glGetIntegerv
  bool GetHelper(GLenum pname, GLint* params, GLsizei* num_written);

  // Helper for glGetVertexAttrib
  void GetVertexAttribHelper(
    const VertexAttrib* attrib, GLenum pname, GLint* param);

  // Wrapper for glCreateProgram
  bool CreateProgramHelper(GLuint client_id);

  // Wrapper for glCreateShader
  bool CreateShaderHelper(GLenum type, GLuint client_id);

  // Wrapper for glActiveTexture
  void DoActiveTexture(GLenum texture_unit);

  // Wrapper for glAttachShader
  void DoAttachShader(GLuint client_program_id, GLint client_shader_id);

  // Wrapper for glBindBuffer since we need to track the current targets.
  void DoBindBuffer(GLenum target, GLuint buffer);

  // Wrapper for glBindFramebuffer since we need to track the current targets.
  void DoBindFramebuffer(GLenum target, GLuint framebuffer);

  // Wrapper for glBindRenderbuffer since we need to track the current targets.
  void DoBindRenderbuffer(GLenum target, GLuint renderbuffer);

  // Wrapper for glBindTexture since we need to track the current targets.
  void DoBindTexture(GLenum target, GLuint texture);

  // Wrapper for glBindVertexArrayOES
  void DoBindVertexArrayOES(GLuint array);
  void EmulateVertexArrayState();

  // Wrapper for glBlitFramebufferCHROMIUM.
  void DoBlitFramebufferCHROMIUM(
      GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1,
      GLint dstX0, GLint dstY0, GLint dstX1, GLint dstY1,
      GLbitfield mask, GLenum filter);

  // Wrapper for glBufferSubData.
  void DoBufferSubData(
    GLenum target, GLintptr offset, GLsizeiptr size, const GLvoid * data);

  // Wrapper for glCheckFramebufferStatus
  GLenum DoCheckFramebufferStatus(GLenum target);

  // Wrapper for glClear
  error::Error DoClear(GLbitfield mask);

  // Wrappers for various state.
  void DoDepthRangef(GLclampf znear, GLclampf zfar);
  void DoSampleCoverage(GLclampf value, GLboolean invert);

  // Wrapper for glCompileShader.
  void DoCompileShader(GLuint shader);

  // Helper for DeleteSharedIdsCHROMIUM commands.
  void DoDeleteSharedIdsCHROMIUM(
      GLuint namespace_id, GLsizei n, const GLuint* ids);

  // Wrapper for glDetachShader
  void DoDetachShader(GLuint client_program_id, GLint client_shader_id);

  // Wrapper for glDisable
  void DoDisable(GLenum cap);

  // Wrapper for glDisableVertexAttribArray.
  void DoDisableVertexAttribArray(GLuint index);

  // Wrapper for glDiscardFramebufferEXT, since we need to track undefined
  // attachments.
  void DoDiscardFramebufferEXT(GLenum target,
                               GLsizei numAttachments,
                               const GLenum* attachments);

  // Wrapper for glEnable
  void DoEnable(GLenum cap);

  // Wrapper for glEnableVertexAttribArray.
  void DoEnableVertexAttribArray(GLuint index);

  // Wrapper for glFinish.
  void DoFinish();

  // Wrapper for glFlush.
  void DoFlush();

  // Wrapper for glFramebufferRenderbufffer.
  void DoFramebufferRenderbuffer(
      GLenum target, GLenum attachment, GLenum renderbuffertarget,
      GLuint renderbuffer);

  // Wrapper for glFramebufferTexture2D.
  void DoFramebufferTexture2D(
      GLenum target, GLenum attachment, GLenum textarget, GLuint texture,
      GLint level);

  // Wrapper for glFramebufferTexture2DMultisampleEXT.
  void DoFramebufferTexture2DMultisample(
      GLenum target, GLenum attachment, GLenum textarget,
      GLuint texture, GLint level, GLsizei samples);

  // Common implementation for both DoFramebufferTexture2D wrappers.
  void DoFramebufferTexture2DCommon(const char* name,
      GLenum target, GLenum attachment, GLenum textarget,
      GLuint texture, GLint level, GLsizei samples);

  // Wrapper for glGenerateMipmap
  void DoGenerateMipmap(GLenum target);

  // Helper for GenSharedIdsCHROMIUM commands.
  void DoGenSharedIdsCHROMIUM(
      GLuint namespace_id, GLuint id_offset, GLsizei n, GLuint* ids);

  // Helper for DoGetBooleanv, Floatv, and Intergerv to adjust pname
  // to account for different pname values defined in different extension
  // variants.
  GLenum AdjustGetPname(GLenum pname);

  // Wrapper for DoGetBooleanv.
  void DoGetBooleanv(GLenum pname, GLboolean* params);

  // Wrapper for DoGetFloatv.
  void DoGetFloatv(GLenum pname, GLfloat* params);

  // Wrapper for glGetFramebufferAttachmentParameteriv.
  void DoGetFramebufferAttachmentParameteriv(
      GLenum target, GLenum attachment, GLenum pname, GLint* params);

  // Wrapper for glGetIntegerv.
  void DoGetIntegerv(GLenum pname, GLint* params);

  // Gets the max value in a range in a buffer.
  GLuint DoGetMaxValueInBufferCHROMIUM(
      GLuint buffer_id, GLsizei count, GLenum type, GLuint offset);

  // Wrapper for glGetBufferParameteriv.
  void DoGetBufferParameteriv(
      GLenum target, GLenum pname, GLint* params);

  // Wrapper for glGetProgramiv.
  void DoGetProgramiv(
      GLuint program_id, GLenum pname, GLint* params);

  // Wrapper for glRenderbufferParameteriv.
  void DoGetRenderbufferParameteriv(
      GLenum target, GLenum pname, GLint* params);

  // Wrapper for glGetShaderiv
  void DoGetShaderiv(GLuint shader, GLenum pname, GLint* params);

  // Wrappers for glGetTexParameter.
  void DoGetTexParameterfv(GLenum target, GLenum pname, GLfloat* params);
  void DoGetTexParameteriv(GLenum target, GLenum pname, GLint* params);
  void InitTextureMaxAnisotropyIfNeeded(GLenum target, GLenum pname);

  // Wrappers for glGetVertexAttrib.
  void DoGetVertexAttribfv(GLuint index, GLenum pname, GLfloat *params);
  void DoGetVertexAttribiv(GLuint index, GLenum pname, GLint *params);

  // Wrappers for glIsXXX functions.
  bool DoIsEnabled(GLenum cap);
  bool DoIsBuffer(GLuint client_id);
  bool DoIsFramebuffer(GLuint client_id);
  bool DoIsProgram(GLuint client_id);
  bool DoIsRenderbuffer(GLuint client_id);
  bool DoIsShader(GLuint client_id);
  bool DoIsTexture(GLuint client_id);
  bool DoIsVertexArrayOES(GLuint client_id);

  // Wrapper for glLinkProgram
  void DoLinkProgram(GLuint program);

  // Helper for RegisterSharedIdsCHROMIUM.
  void DoRegisterSharedIdsCHROMIUM(
      GLuint namespace_id, GLsizei n, const GLuint* ids);

  // Wrapper for glRenderbufferStorage.
  void DoRenderbufferStorage(
      GLenum target, GLenum internalformat, GLsizei width, GLsizei height);

  // Handler for glRenderbufferStorageMultisampleCHROMIUM.
  void DoRenderbufferStorageMultisampleCHROMIUM(
      GLenum target, GLsizei samples, GLenum internalformat,
      GLsizei width, GLsizei height);

  // Handler for glRenderbufferStorageMultisampleEXT
  // (multisampled_render_to_texture).
  void DoRenderbufferStorageMultisampleEXT(
      GLenum target, GLsizei samples, GLenum internalformat,
      GLsizei width, GLsizei height);

  // Common validation for multisample extensions.
  bool ValidateRenderbufferStorageMultisample(GLsizei samples,
                                              GLenum internalformat,
                                              GLsizei width,
                                              GLsizei height);

  // Verifies that the currently bound multisample renderbuffer is valid
  // Very slow! Only done on platforms with driver bugs that return invalid
  // buffers under memory pressure
  bool VerifyMultisampleRenderbufferIntegrity(
      GLuint renderbuffer, GLenum format);

  // Wrapper for glReleaseShaderCompiler.
  void DoReleaseShaderCompiler() { }

  // Wrappers for glTexParameter functions.
  void DoTexParameterf(GLenum target, GLenum pname, GLfloat param);
  void DoTexParameteri(GLenum target, GLenum pname, GLint param);
  void DoTexParameterfv(GLenum target, GLenum pname, const GLfloat* params);
  void DoTexParameteriv(GLenum target, GLenum pname, const GLint* params);

  // Wrappers for glUniform1i and glUniform1iv as according to the GLES2
  // spec only these 2 functions can be used to set sampler uniforms.
  void DoUniform1i(GLint fake_location, GLint v0);
  void DoUniform1iv(GLint fake_location, GLsizei count, const GLint* value);
  void DoUniform2iv(GLint fake_location, GLsizei count, const GLint* value);
  void DoUniform3iv(GLint fake_location, GLsizei count, const GLint* value);
  void DoUniform4iv(GLint fake_location, GLsizei count, const GLint* value);

  // Wrappers for glUniformfv because some drivers don't correctly accept
  // bool uniforms.
  void DoUniform1fv(GLint fake_location, GLsizei count, const GLfloat* value);
  void DoUniform2fv(GLint fake_location, GLsizei count, const GLfloat* value);
  void DoUniform3fv(GLint fake_location, GLsizei count, const GLfloat* value);
  void DoUniform4fv(GLint fake_location, GLsizei count, const GLfloat* value);

  void DoUniformMatrix2fv(
      GLint fake_location, GLsizei count, GLboolean transpose,
      const GLfloat* value);
  void DoUniformMatrix3fv(
      GLint fake_location, GLsizei count, GLboolean transpose,
      const GLfloat* value);
  void DoUniformMatrix4fv(
      GLint fake_location, GLsizei count, GLboolean transpose,
      const GLfloat* value);

  bool SetVertexAttribValue(
    const char* function_name, GLuint index, const GLfloat* value);

  // Wrappers for glVertexAttrib??
  void DoVertexAttrib1f(GLuint index, GLfloat v0);
  void DoVertexAttrib2f(GLuint index, GLfloat v0, GLfloat v1);
  void DoVertexAttrib3f(GLuint index, GLfloat v0, GLfloat v1, GLfloat v2);
  void DoVertexAttrib4f(
      GLuint index, GLfloat v0, GLfloat v1, GLfloat v2, GLfloat v3);
  void DoVertexAttrib1fv(GLuint index, const GLfloat *v);
  void DoVertexAttrib2fv(GLuint index, const GLfloat *v);
  void DoVertexAttrib3fv(GLuint index, const GLfloat *v);
  void DoVertexAttrib4fv(GLuint index, const GLfloat *v);

  // Wrapper for glViewport
  void DoViewport(GLint x, GLint y, GLsizei width, GLsizei height);

  // Wrapper for glUseProgram
  void DoUseProgram(GLuint program);

  // Wrapper for glValidateProgram.
  void DoValidateProgram(GLuint program_client_id);

  void DoInsertEventMarkerEXT(GLsizei length, const GLchar* marker);
  void DoPushGroupMarkerEXT(GLsizei length, const GLchar* group);
  void DoPopGroupMarkerEXT(void);

  // Gets the number of values that will be returned by glGetXXX. Returns
  // false if pname is unknown.
  bool GetNumValuesReturnedForGLGet(GLenum pname, GLsizei* num_values);

  // Checks if the current program and vertex attributes are valid for drawing.
  bool IsDrawValid(
      const char* function_name, GLuint max_vertex_accessed, GLsizei primcount);

  // Returns true if successful, simulated will be true if attrib0 was
  // simulated.
  bool SimulateAttrib0(
      const char* function_name, GLuint max_vertex_accessed, bool* simulated);
  void RestoreStateForAttrib(GLuint attrib, bool restore_array_binding);

  // If an image is bound to texture, this will call Will/DidUseTexImage
  // if needed.
  void DoWillUseTexImageIfNeeded(Texture* texture, GLenum textarget);
  void DoDidUseTexImageIfNeeded(Texture* texture, GLenum textarget);

  // Returns false if textures were replaced.
  bool PrepareTexturesForRender();
  void RestoreStateForTextures();

  // Returns true if GL_FIXED attribs were simulated.
  bool SimulateFixedAttribs(
      const char* function_name,
      GLuint max_vertex_accessed, bool* simulated, GLsizei primcount);
  void RestoreStateForSimulatedFixedAttribs();

  // Handle DrawArrays and DrawElements for both instanced and non-instanced
  // cases (primcount is 0 for non-instanced).
  error::Error DoDrawArrays(
      const char* function_name,
      bool instanced, GLenum mode, GLint first, GLsizei count,
      GLsizei primcount);
  error::Error DoDrawElements(
      const char* function_name,
      bool instanced, GLenum mode, GLsizei count, GLenum type,
      int32 offset, GLsizei primcount);

  GLenum GetBindTargetForSamplerType(GLenum type) {
    DCHECK(type == GL_SAMPLER_2D || type == GL_SAMPLER_CUBE ||
           type == GL_SAMPLER_EXTERNAL_OES || type == GL_SAMPLER_2D_RECT_ARB);
    switch (type) {
      case GL_SAMPLER_2D:
        return GL_TEXTURE_2D;
      case GL_SAMPLER_CUBE:
        return GL_TEXTURE_CUBE_MAP;
      case GL_SAMPLER_EXTERNAL_OES:
        return GL_TEXTURE_EXTERNAL_OES;
      case GL_SAMPLER_2D_RECT_ARB:
        return GL_TEXTURE_RECTANGLE_ARB;
    }

    NOTREACHED();
    return 0;
  }

  // Gets the framebuffer info for a particular target.
  Framebuffer* GetFramebufferInfoForTarget(GLenum target) {
    Framebuffer* framebuffer = NULL;
    switch (target) {
      case GL_FRAMEBUFFER:
      case GL_DRAW_FRAMEBUFFER_EXT:
        framebuffer = framebuffer_state_.bound_draw_framebuffer.get();
        break;
      case GL_READ_FRAMEBUFFER_EXT:
        framebuffer = framebuffer_state_.bound_read_framebuffer.get();
        break;
      default:
        NOTREACHED();
        break;
    }
    return framebuffer;
  }

  Renderbuffer* GetRenderbufferInfoForTarget(
      GLenum target) {
    Renderbuffer* renderbuffer = NULL;
    switch (target) {
      case GL_RENDERBUFFER:
        renderbuffer = state_.bound_renderbuffer.get();
        break;
      default:
        NOTREACHED();
        break;
    }
    return renderbuffer;
  }

  // Validates the program and location for a glGetUniform call and returns
  // a SizeResult setup to receive the result. Returns true if glGetUniform
  // should be called.
  bool GetUniformSetup(
      GLuint program, GLint fake_location,
      uint32 shm_id, uint32 shm_offset,
      error::Error* error, GLint* real_location, GLuint* service_id,
      void** result, GLenum* result_type);

  virtual bool WasContextLost() OVERRIDE;
  virtual bool WasContextLostByRobustnessExtension() OVERRIDE;
  virtual void LoseContext(uint32 reset_status) OVERRIDE;

#if defined(OS_MACOSX)
  void ReleaseIOSurfaceForTexture(GLuint texture_id);
#endif

  bool ValidateCompressedTexDimensions(
      const char* function_name,
      GLint level, GLsizei width, GLsizei height, GLenum format);
  bool ValidateCompressedTexFuncData(
      const char* function_name,
      GLsizei width, GLsizei height, GLenum format, size_t size);
  bool ValidateCompressedTexSubDimensions(
    const char* function_name,
    GLenum target, GLint level, GLint xoffset, GLint yoffset,
    GLsizei width, GLsizei height, GLenum format,
    Texture* texture);

  void RenderWarning(const char* filename, int line, const std::string& msg);
  void PerformanceWarning(
      const char* filename, int line, const std::string& msg);

  const FeatureInfo::FeatureFlags& features() const {
    return feature_info_->feature_flags();
  }

  const FeatureInfo::Workarounds& workarounds() const {
    return feature_info_->workarounds();
  }

  bool ShouldDeferDraws() {
    return !offscreen_target_frame_buffer_.get() &&
           framebuffer_state_.bound_draw_framebuffer.get() == NULL &&
           surface_->DeferDraws();
  }

  bool ShouldDeferReads() {
    return !offscreen_target_frame_buffer_.get() &&
           framebuffer_state_.bound_read_framebuffer.get() == NULL &&
           surface_->DeferDraws();
  }

  error::Error WillAccessBoundFramebufferForDraw() {
    if (ShouldDeferDraws())
      return error::kDeferCommandUntilLater;
    if (!offscreen_target_frame_buffer_.get() &&
        !framebuffer_state_.bound_draw_framebuffer.get() &&
        !surface_->SetBackbufferAllocation(true))
      return error::kLostContext;
    return error::kNoError;
  }

  error::Error WillAccessBoundFramebufferForRead() {
    if (ShouldDeferReads())
      return error::kDeferCommandUntilLater;
    if (!offscreen_target_frame_buffer_.get() &&
        !framebuffer_state_.bound_read_framebuffer.get() &&
        !surface_->SetBackbufferAllocation(true))
      return error::kLostContext;
    return error::kNoError;
  }

  void ProcessPendingReadPixels();
  void FinishReadPixels(const cmds::ReadPixels& c, GLuint buffer);

  // Generate a member function prototype for each command in an automated and
  // typesafe way.
  #define GLES2_CMD_OP(name) \
     Error Handle ## name(             \
       uint32 immediate_data_size,     \
       const cmds::name& args);        \

  GLES2_COMMAND_LIST(GLES2_CMD_OP)

  #undef GLES2_CMD_OP

  // The GL context this decoder renders to on behalf of the client.
  scoped_refptr<gfx::GLSurface> surface_;
  scoped_refptr<gfx::GLContext> context_;

  // The ContextGroup for this decoder uses to track resources.
  scoped_refptr<ContextGroup> group_;

  DebugMarkerManager debug_marker_manager_;
  Logger logger_;

  // All the state for this context.
  ContextState state_;

  // Current width and height of the offscreen frame buffer.
  gfx::Size offscreen_size_;

  // Util to help with GL.
  GLES2Util util_;

  // unpack flip y as last set by glPixelStorei
  bool unpack_flip_y_;

  // unpack (un)premultiply alpha as last set by glPixelStorei
  bool unpack_premultiply_alpha_;
  bool unpack_unpremultiply_alpha_;

  // The buffer we bind to attrib 0 since OpenGL requires it (ES does not).
  GLuint attrib_0_buffer_id_;

  // The value currently in attrib_0.
  Vec4 attrib_0_value_;

  // Whether or not the attrib_0 buffer holds the attrib_0_value.
  bool attrib_0_buffer_matches_value_;

  // The size of attrib 0.
  GLsizei attrib_0_size_;

  // The buffer used to simulate GL_FIXED attribs.
  GLuint fixed_attrib_buffer_id_;

  // The size of fiixed attrib buffer.
  GLsizei fixed_attrib_buffer_size_;

  // The offscreen frame buffer that the client renders to. With EGL, the
  // depth and stencil buffers are separate. With regular GL there is a single
  // packed depth stencil buffer in offscreen_target_depth_render_buffer_.
  // offscreen_target_stencil_render_buffer_ is unused.
  scoped_ptr<BackFramebuffer> offscreen_target_frame_buffer_;
  scoped_ptr<BackTexture> offscreen_target_color_texture_;
  scoped_ptr<BackRenderbuffer> offscreen_target_color_render_buffer_;
  scoped_ptr<BackRenderbuffer> offscreen_target_depth_render_buffer_;
  scoped_ptr<BackRenderbuffer> offscreen_target_stencil_render_buffer_;
  GLenum offscreen_target_color_format_;
  GLenum offscreen_target_depth_format_;
  GLenum offscreen_target_stencil_format_;
  GLsizei offscreen_target_samples_;
  GLboolean offscreen_target_buffer_preserved_;

  // The copy that is saved when SwapBuffers is called.
  scoped_ptr<BackFramebuffer> offscreen_saved_frame_buffer_;
  scoped_ptr<BackTexture> offscreen_saved_color_texture_;
  scoped_refptr<TextureRef>
      offscreen_saved_color_texture_info_;

  // The copy that is used as the destination for multi-sample resolves.
  scoped_ptr<BackFramebuffer> offscreen_resolved_frame_buffer_;
  scoped_ptr<BackTexture> offscreen_resolved_color_texture_;
  GLenum offscreen_saved_color_format_;

  scoped_ptr<QueryManager> query_manager_;

  scoped_ptr<VertexArrayManager> vertex_array_manager_;

  base::Callback<void(gfx::Size, float)> resize_callback_;

  WaitSyncPointCallback wait_sync_point_callback_;

  ShaderCacheCallback shader_cache_callback_;

  scoped_ptr<AsyncPixelTransferManager> async_pixel_transfer_manager_;

  // The format of the back buffer_
  GLenum back_buffer_color_format_;
  bool back_buffer_has_depth_;
  bool back_buffer_has_stencil_;

  // Backbuffer attachments that are currently undefined.
  uint32 backbuffer_needs_clear_bits_;

  // The current decoder error communicates the decoder error through command
  // processing functions that do not return the error value. Should be set only
  // if not returning an error.
  error::Error current_decoder_error_;

  bool use_shader_translator_;
  scoped_refptr<ShaderTranslator> vertex_translator_;
  scoped_refptr<ShaderTranslator> fragment_translator_;

  DisallowedFeatures disallowed_features_;

  // Cached from ContextGroup
  const Validators* validators_;
  scoped_refptr<FeatureInfo> feature_info_;

  int frame_number_;

  bool has_robustness_extension_;
  GLenum reset_status_;
  bool reset_by_robustness_extension_;
  bool supports_post_sub_buffer_;

  // These flags are used to override the state of the shared feature_info_
  // member.  Because the same FeatureInfo instance may be shared among many
  // contexts, the assumptions on the availablity of extensions in WebGL
  // contexts may be broken.  These flags override the shared state to preserve
  // WebGL semantics.
  bool force_webgl_glsl_validation_;
  bool derivatives_explicitly_enabled_;
  bool frag_depth_explicitly_enabled_;
  bool draw_buffers_explicitly_enabled_;
  bool shader_texture_lod_explicitly_enabled_;

  bool compile_shader_always_succeeds_;

  // An optional behaviour to lose the context and group when OOM.
  bool lose_context_when_out_of_memory_;

  // Log extra info.
  bool service_logging_;

#if defined(OS_MACOSX)
  typedef std::map<GLuint, IOSurfaceRef> TextureToIOSurfaceMap;
  TextureToIOSurfaceMap texture_to_io_surface_map_;
#endif

  scoped_ptr<CopyTextureCHROMIUMResourceManager> copy_texture_CHROMIUM_;

  // Cached values of the currently assigned viewport dimensions.
  GLsizei viewport_max_width_;
  GLsizei viewport_max_height_;

  // Command buffer stats.
  base::TimeDelta total_processing_commands_time_;

  // States related to each manager.
  DecoderTextureState texture_state_;
  DecoderFramebufferState framebuffer_state_;

  scoped_ptr<GPUTracer> gpu_tracer_;
  scoped_ptr<GPUStateTracer> gpu_state_tracer_;
  int gpu_trace_level_;
  bool gpu_trace_commands_;

  std::queue<linked_ptr<FenceCallback> > pending_readpixel_fences_;

  // Used to validate multisample renderbuffers if needed
  GLuint validation_texture_;
  GLuint validation_fbo_multisample_;
  GLuint validation_fbo_;

  DISALLOW_COPY_AND_ASSIGN(GLES2DecoderImpl);
};

ScopedGLErrorSuppressor::ScopedGLErrorSuppressor(
    const char* function_name, ErrorState* error_state)
    : function_name_(function_name),
      error_state_(error_state) {
  ERRORSTATE_COPY_REAL_GL_ERRORS_TO_WRAPPER(error_state_, function_name_);
}

ScopedGLErrorSuppressor::~ScopedGLErrorSuppressor() {
  ERRORSTATE_CLEAR_REAL_GL_ERRORS(error_state_, function_name_);
}

static void RestoreCurrentTextureBindings(ContextState* state, GLenum target) {
  TextureUnit& info = state->texture_units[0];
  GLuint last_id;
  scoped_refptr<TextureRef> texture_ref;
  switch (target) {
    case GL_TEXTURE_2D:
      texture_ref = info.bound_texture_2d;
      break;
    case GL_TEXTURE_CUBE_MAP:
      texture_ref = info.bound_texture_cube_map;
      break;
    case GL_TEXTURE_EXTERNAL_OES:
      texture_ref = info.bound_texture_external_oes;
      break;
    case GL_TEXTURE_RECTANGLE_ARB:
      texture_ref = info.bound_texture_rectangle_arb;
      break;
    default:
      NOTREACHED();
      break;
  }
  if (texture_ref.get()) {
    last_id = texture_ref->service_id();
  } else {
    last_id = 0;
  }

  glBindTexture(target, last_id);
  glActiveTexture(GL_TEXTURE0 + state->active_texture_unit);
}

ScopedTextureBinder::ScopedTextureBinder(ContextState* state,
                                         GLuint id,
                                         GLenum target)
    : state_(state),
      target_(target) {
  ScopedGLErrorSuppressor suppressor(
      "ScopedTextureBinder::ctor", state_->GetErrorState());

  // TODO(apatrick): Check if there are any other states that need to be reset
  // before binding a new texture.
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(target, id);
}

ScopedTextureBinder::~ScopedTextureBinder() {
  ScopedGLErrorSuppressor suppressor(
      "ScopedTextureBinder::dtor", state_->GetErrorState());
  RestoreCurrentTextureBindings(state_, target_);
}

ScopedRenderBufferBinder::ScopedRenderBufferBinder(ContextState* state,
                                                   GLuint id)
    : state_(state) {
  ScopedGLErrorSuppressor suppressor(
      "ScopedRenderBufferBinder::ctor", state_->GetErrorState());
  glBindRenderbufferEXT(GL_RENDERBUFFER, id);
}

ScopedRenderBufferBinder::~ScopedRenderBufferBinder() {
  ScopedGLErrorSuppressor suppressor(
      "ScopedRenderBufferBinder::dtor", state_->GetErrorState());
  state_->RestoreRenderbufferBindings();
}

ScopedFrameBufferBinder::ScopedFrameBufferBinder(GLES2DecoderImpl* decoder,
                                                 GLuint id)
    : decoder_(decoder) {
  ScopedGLErrorSuppressor suppressor(
      "ScopedFrameBufferBinder::ctor", decoder_->GetErrorState());
  glBindFramebufferEXT(GL_FRAMEBUFFER, id);
  decoder->OnFboChanged();
}

ScopedFrameBufferBinder::~ScopedFrameBufferBinder() {
  ScopedGLErrorSuppressor suppressor(
      "ScopedFrameBufferBinder::dtor", decoder_->GetErrorState());
  decoder_->RestoreCurrentFramebufferBindings();
}

ScopedResolvedFrameBufferBinder::ScopedResolvedFrameBufferBinder(
    GLES2DecoderImpl* decoder, bool enforce_internal_framebuffer, bool internal)
    : decoder_(decoder) {
  resolve_and_bind_ = (
      decoder_->offscreen_target_frame_buffer_.get() &&
      decoder_->IsOffscreenBufferMultisampled() &&
      (!decoder_->framebuffer_state_.bound_read_framebuffer.get() ||
       enforce_internal_framebuffer));
  if (!resolve_and_bind_)
    return;

  ScopedGLErrorSuppressor suppressor(
      "ScopedResolvedFrameBufferBinder::ctor", decoder_->GetErrorState());
  glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT,
                       decoder_->offscreen_target_frame_buffer_->id());
  GLuint targetid;
  if (internal) {
    if (!decoder_->offscreen_resolved_frame_buffer_.get()) {
      decoder_->offscreen_resolved_frame_buffer_.reset(
          new BackFramebuffer(decoder_));
      decoder_->offscreen_resolved_frame_buffer_->Create();
      decoder_->offscreen_resolved_color_texture_.reset(
          new BackTexture(decoder->memory_tracker(), &decoder->state_));
      decoder_->offscreen_resolved_color_texture_->Create();

      DCHECK(decoder_->offscreen_saved_color_format_);
      decoder_->offscreen_resolved_color_texture_->AllocateStorage(
          decoder_->offscreen_size_, decoder_->offscreen_saved_color_format_,
          false);
      decoder_->offscreen_resolved_frame_buffer_->AttachRenderTexture(
          decoder_->offscreen_resolved_color_texture_.get());
      if (decoder_->offscreen_resolved_frame_buffer_->CheckStatus() !=
          GL_FRAMEBUFFER_COMPLETE) {
        LOG(ERROR) << "ScopedResolvedFrameBufferBinder failed "
                   << "because offscreen resolved FBO was incomplete.";
        return;
      }
    }
    targetid = decoder_->offscreen_resolved_frame_buffer_->id();
  } else {
    targetid = decoder_->offscreen_saved_frame_buffer_->id();
  }
  glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, targetid);
  const int width = decoder_->offscreen_size_.width();
  const int height = decoder_->offscreen_size_.height();
  decoder->state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, false);
  decoder->BlitFramebufferHelper(0,
                                 0,
                                 width,
                                 height,
                                 0,
                                 0,
                                 width,
                                 height,
                                 GL_COLOR_BUFFER_BIT,
                                 GL_NEAREST);
  glBindFramebufferEXT(GL_FRAMEBUFFER, targetid);
}

ScopedResolvedFrameBufferBinder::~ScopedResolvedFrameBufferBinder() {
  if (!resolve_and_bind_)
    return;

  ScopedGLErrorSuppressor suppressor(
      "ScopedResolvedFrameBufferBinder::dtor", decoder_->GetErrorState());
  decoder_->RestoreCurrentFramebufferBindings();
  if (decoder_->state_.enable_flags.scissor_test) {
    decoder_->state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, true);
  }
}

BackTexture::BackTexture(
    MemoryTracker* memory_tracker,
    ContextState* state)
    : memory_tracker_(memory_tracker, MemoryTracker::kUnmanaged),
      state_(state),
      bytes_allocated_(0),
      id_(0) {
}

BackTexture::~BackTexture() {
  // This does not destroy the render texture because that would require that
  // the associated GL context was current. Just check that it was explicitly
  // destroyed.
  DCHECK_EQ(id_, 0u);
}

void BackTexture::Create() {
  ScopedGLErrorSuppressor suppressor("BackTexture::Create",
                                     state_->GetErrorState());
  Destroy();
  glGenTextures(1, &id_);
  ScopedTextureBinder binder(state_, id_, GL_TEXTURE_2D);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

  // TODO(apatrick): Attempt to diagnose crbug.com/97775. If SwapBuffers is
  // never called on an offscreen context, no data will ever be uploaded to the
  // saved offscreen color texture (it is deferred until to when SwapBuffers
  // is called). My idea is that some nvidia drivers might have a bug where
  // deleting a texture that has never been populated might cause a
  // crash.
  glTexImage2D(
      GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);

  bytes_allocated_ = 16u * 16u * 4u;
  memory_tracker_.TrackMemAlloc(bytes_allocated_);
}

bool BackTexture::AllocateStorage(
    const gfx::Size& size, GLenum format, bool zero) {
  DCHECK_NE(id_, 0u);
  ScopedGLErrorSuppressor suppressor("BackTexture::AllocateStorage",
                                     state_->GetErrorState());
  ScopedTextureBinder binder(state_, id_, GL_TEXTURE_2D);
  uint32 image_size = 0;
  GLES2Util::ComputeImageDataSizes(
      size.width(), size.height(), format, GL_UNSIGNED_BYTE, 8, &image_size,
      NULL, NULL);

  if (!memory_tracker_.EnsureGPUMemoryAvailable(image_size)) {
    return false;
  }

  scoped_ptr<char[]> zero_data;
  if (zero) {
    zero_data.reset(new char[image_size]);
    memset(zero_data.get(), 0, image_size);
  }

  glTexImage2D(GL_TEXTURE_2D,
               0,  // mip level
               format,
               size.width(),
               size.height(),
               0,  // border
               format,
               GL_UNSIGNED_BYTE,
               zero_data.get());

  size_ = size;

  bool success = glGetError() == GL_NO_ERROR;
  if (success) {
    memory_tracker_.TrackMemFree(bytes_allocated_);
    bytes_allocated_ = image_size;
    memory_tracker_.TrackMemAlloc(bytes_allocated_);
  }
  return success;
}

void BackTexture::Copy(const gfx::Size& size, GLenum format) {
  DCHECK_NE(id_, 0u);
  ScopedGLErrorSuppressor suppressor("BackTexture::Copy",
                                     state_->GetErrorState());
  ScopedTextureBinder binder(state_, id_, GL_TEXTURE_2D);
  glCopyTexImage2D(GL_TEXTURE_2D,
                   0,  // level
                   format,
                   0, 0,
                   size.width(),
                   size.height(),
                   0);  // border
}

void BackTexture::Destroy() {
  if (id_ != 0) {
    ScopedGLErrorSuppressor suppressor("BackTexture::Destroy",
                                       state_->GetErrorState());
    glDeleteTextures(1, &id_);
    id_ = 0;
  }
  memory_tracker_.TrackMemFree(bytes_allocated_);
  bytes_allocated_ = 0;
}

void BackTexture::Invalidate() {
  id_ = 0;
}

BackRenderbuffer::BackRenderbuffer(
    RenderbufferManager* renderbuffer_manager,
    MemoryTracker* memory_tracker,
    ContextState* state)
    : renderbuffer_manager_(renderbuffer_manager),
      memory_tracker_(memory_tracker, MemoryTracker::kUnmanaged),
      state_(state),
      bytes_allocated_(0),
      id_(0) {
}

BackRenderbuffer::~BackRenderbuffer() {
  // This does not destroy the render buffer because that would require that
  // the associated GL context was current. Just check that it was explicitly
  // destroyed.
  DCHECK_EQ(id_, 0u);
}

void BackRenderbuffer::Create() {
  ScopedGLErrorSuppressor suppressor("BackRenderbuffer::Create",
                                     state_->GetErrorState());
  Destroy();
  glGenRenderbuffersEXT(1, &id_);
}

bool BackRenderbuffer::AllocateStorage(const FeatureInfo* feature_info,
                                       const gfx::Size& size,
                                       GLenum format,
                                       GLsizei samples) {
  ScopedGLErrorSuppressor suppressor(
      "BackRenderbuffer::AllocateStorage", state_->GetErrorState());
  ScopedRenderBufferBinder binder(state_, id_);

  uint32 estimated_size = 0;
  if (!renderbuffer_manager_->ComputeEstimatedRenderbufferSize(
           size.width(), size.height(), samples, format, &estimated_size)) {
    return false;
  }

  if (!memory_tracker_.EnsureGPUMemoryAvailable(estimated_size)) {
    return false;
  }

  if (samples <= 1) {
    glRenderbufferStorageEXT(GL_RENDERBUFFER,
                             format,
                             size.width(),
                             size.height());
  } else {
    GLES2DecoderImpl::RenderbufferStorageMultisampleHelper(feature_info,
                                                           GL_RENDERBUFFER,
                                                           samples,
                                                           format,
                                                           size.width(),
                                                           size.height());
  }
  bool success = glGetError() == GL_NO_ERROR;
  if (success) {
    // Mark the previously allocated bytes as free.
    memory_tracker_.TrackMemFree(bytes_allocated_);
    bytes_allocated_ = estimated_size;
    // Track the newly allocated bytes.
    memory_tracker_.TrackMemAlloc(bytes_allocated_);
  }
  return success;
}

void BackRenderbuffer::Destroy() {
  if (id_ != 0) {
    ScopedGLErrorSuppressor suppressor("BackRenderbuffer::Destroy",
                                       state_->GetErrorState());
    glDeleteRenderbuffersEXT(1, &id_);
    id_ = 0;
  }
  memory_tracker_.TrackMemFree(bytes_allocated_);
  bytes_allocated_ = 0;
}

void BackRenderbuffer::Invalidate() {
  id_ = 0;
}

BackFramebuffer::BackFramebuffer(GLES2DecoderImpl* decoder)
    : decoder_(decoder),
      id_(0) {
}

BackFramebuffer::~BackFramebuffer() {
  // This does not destroy the frame buffer because that would require that
  // the associated GL context was current. Just check that it was explicitly
  // destroyed.
  DCHECK_EQ(id_, 0u);
}

void BackFramebuffer::Create() {
  ScopedGLErrorSuppressor suppressor("BackFramebuffer::Create",
                                     decoder_->GetErrorState());
  Destroy();
  glGenFramebuffersEXT(1, &id_);
}

void BackFramebuffer::AttachRenderTexture(BackTexture* texture) {
  DCHECK_NE(id_, 0u);
  ScopedGLErrorSuppressor suppressor(
      "BackFramebuffer::AttachRenderTexture", decoder_->GetErrorState());
  ScopedFrameBufferBinder binder(decoder_, id_);
  GLuint attach_id = texture ? texture->id() : 0;
  glFramebufferTexture2DEXT(GL_FRAMEBUFFER,
                            GL_COLOR_ATTACHMENT0,
                            GL_TEXTURE_2D,
                            attach_id,
                            0);
}

void BackFramebuffer::AttachRenderBuffer(GLenum target,
                                         BackRenderbuffer* render_buffer) {
  DCHECK_NE(id_, 0u);
  ScopedGLErrorSuppressor suppressor(
      "BackFramebuffer::AttachRenderBuffer", decoder_->GetErrorState());
  ScopedFrameBufferBinder binder(decoder_, id_);
  GLuint attach_id = render_buffer ? render_buffer->id() : 0;
  glFramebufferRenderbufferEXT(GL_FRAMEBUFFER,
                               target,
                               GL_RENDERBUFFER,
                               attach_id);
}

void BackFramebuffer::Destroy() {
  if (id_ != 0) {
    ScopedGLErrorSuppressor suppressor("BackFramebuffer::Destroy",
                                       decoder_->GetErrorState());
    glDeleteFramebuffersEXT(1, &id_);
    id_ = 0;
  }
}

void BackFramebuffer::Invalidate() {
  id_ = 0;
}

GLenum BackFramebuffer::CheckStatus() {
  DCHECK_NE(id_, 0u);
  ScopedGLErrorSuppressor suppressor("BackFramebuffer::CheckStatus",
                                     decoder_->GetErrorState());
  ScopedFrameBufferBinder binder(decoder_, id_);
  return glCheckFramebufferStatusEXT(GL_FRAMEBUFFER);
}

GLES2Decoder* GLES2Decoder::Create(ContextGroup* group) {
  return new GLES2DecoderImpl(group);
}

GLES2DecoderImpl::GLES2DecoderImpl(ContextGroup* group)
    : GLES2Decoder(),
      group_(group),
      logger_(&debug_marker_manager_),
      state_(group_->feature_info(), this, &logger_),
      unpack_flip_y_(false),
      unpack_premultiply_alpha_(false),
      unpack_unpremultiply_alpha_(false),
      attrib_0_buffer_id_(0),
      attrib_0_buffer_matches_value_(true),
      attrib_0_size_(0),
      fixed_attrib_buffer_id_(0),
      fixed_attrib_buffer_size_(0),
      offscreen_target_color_format_(0),
      offscreen_target_depth_format_(0),
      offscreen_target_stencil_format_(0),
      offscreen_target_samples_(0),
      offscreen_target_buffer_preserved_(true),
      offscreen_saved_color_format_(0),
      back_buffer_color_format_(0),
      back_buffer_has_depth_(false),
      back_buffer_has_stencil_(false),
      backbuffer_needs_clear_bits_(0),
      current_decoder_error_(error::kNoError),
      use_shader_translator_(true),
      validators_(group_->feature_info()->validators()),
      feature_info_(group_->feature_info()),
      frame_number_(0),
      has_robustness_extension_(false),
      reset_status_(GL_NO_ERROR),
      reset_by_robustness_extension_(false),
      supports_post_sub_buffer_(false),
      force_webgl_glsl_validation_(false),
      derivatives_explicitly_enabled_(false),
      frag_depth_explicitly_enabled_(false),
      draw_buffers_explicitly_enabled_(false),
      shader_texture_lod_explicitly_enabled_(false),
      compile_shader_always_succeeds_(false),
      lose_context_when_out_of_memory_(false),
      service_logging_(CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kEnableGPUServiceLoggingGPU)),
      viewport_max_width_(0),
      viewport_max_height_(0),
      texture_state_(group_->feature_info()
                         ->workarounds()
                         .texsubimage2d_faster_than_teximage2d),
      validation_texture_(0),
      validation_fbo_multisample_(0),
      validation_fbo_(0) {
  DCHECK(group);

  attrib_0_value_.v[0] = 0.0f;
  attrib_0_value_.v[1] = 0.0f;
  attrib_0_value_.v[2] = 0.0f;
  attrib_0_value_.v[3] = 1.0f;

  // The shader translator is used for WebGL even when running on EGL
  // because additional restrictions are needed (like only enabling
  // GL_OES_standard_derivatives on demand).  It is used for the unit
  // tests because GLES2DecoderWithShaderTest.GetShaderInfoLogValidArgs passes
  // the empty string to CompileShader and this is not a valid shader.
  if (gfx::GetGLImplementation() == gfx::kGLImplementationMockGL ||
      CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kDisableGLSLTranslator)) {
    use_shader_translator_ = false;
  }
}

GLES2DecoderImpl::~GLES2DecoderImpl() {
}

bool GLES2DecoderImpl::Initialize(
    const scoped_refptr<gfx::GLSurface>& surface,
    const scoped_refptr<gfx::GLContext>& context,
    bool offscreen,
    const gfx::Size& size,
    const DisallowedFeatures& disallowed_features,
    const std::vector<int32>& attribs) {
  TRACE_EVENT0("gpu", "GLES2DecoderImpl::Initialize");
  DCHECK(context->IsCurrent(surface.get()));
  DCHECK(!context_.get());

  set_initialized();
  gpu_tracer_ = GPUTracer::Create(this);
  gpu_state_tracer_ = GPUStateTracer::Create(&state_);
  // TODO(vmiura): Enable changing gpu_trace_level_ at runtime
  gpu_trace_level_ = 2;
  gpu_trace_commands_ = false;

  if (CommandLine::ForCurrentProcess()->HasSwitch(
      switches::kEnableGPUDebugging)) {
    set_debug(true);
  }

  if (CommandLine::ForCurrentProcess()->HasSwitch(
      switches::kEnableGPUCommandLogging)) {
    set_log_commands(true);
  }

  compile_shader_always_succeeds_ = CommandLine::ForCurrentProcess()->HasSwitch(
      switches::kCompileShaderAlwaysSucceeds);


  // Take ownership of the context and surface. The surface can be replaced with
  // SetSurface.
  context_ = context;
  surface_ = surface;

  ContextCreationAttribHelper attrib_parser;
  if (!attrib_parser.Parse(attribs))
    return false;

  // Save the loseContextWhenOutOfMemory context creation attribute.
  lose_context_when_out_of_memory_ =
      attrib_parser.lose_context_when_out_of_memory_;

  // If the failIfMajorPerformanceCaveat context creation attribute was true
  // and we are using a software renderer, fail.
  if (attrib_parser.fail_if_major_perf_caveat_ &&
      feature_info_->feature_flags().is_swiftshader) {
    group_ = NULL;  // Must not destroy ContextGroup if it is not initialized.
    Destroy(true);
    return false;
  }

  if (!group_->Initialize(this, disallowed_features)) {
    LOG(ERROR) << "GpuScheduler::InitializeCommon failed because group "
               << "failed to initialize.";
    group_ = NULL;  // Must not destroy ContextGroup if it is not initialized.
    Destroy(true);
    return false;
  }
  CHECK_GL_ERROR();

  disallowed_features_ = disallowed_features;

  state_.attrib_values.resize(group_->max_vertex_attribs());
  vertex_array_manager_.reset(new VertexArrayManager());

  GLuint default_vertex_attrib_service_id = 0;
  if (features().native_vertex_array_object) {
    glGenVertexArraysOES(1, &default_vertex_attrib_service_id);
    glBindVertexArrayOES(default_vertex_attrib_service_id);
  }

  state_.default_vertex_attrib_manager =
      CreateVertexAttribManager(0, default_vertex_attrib_service_id, false);

  state_.default_vertex_attrib_manager->Initialize(
      group_->max_vertex_attribs(),
      feature_info_->workarounds().init_vertex_attributes);

  // vertex_attrib_manager is set to default_vertex_attrib_manager by this call
  DoBindVertexArrayOES(0);

  query_manager_.reset(new QueryManager(this, feature_info_.get()));

  util_.set_num_compressed_texture_formats(
      validators_->compressed_texture_format.GetValues().size());

  if (gfx::GetGLImplementation() != gfx::kGLImplementationEGLGLES2) {
    // We have to enable vertex array 0 on OpenGL or it won't render. Note that
    // OpenGL ES 2.0 does not have this issue.
    glEnableVertexAttribArray(0);
  }
  glGenBuffersARB(1, &attrib_0_buffer_id_);
  glBindBuffer(GL_ARRAY_BUFFER, attrib_0_buffer_id_);
  glVertexAttribPointer(0, 1, GL_FLOAT, GL_FALSE, 0, NULL);
  glBindBuffer(GL_ARRAY_BUFFER, 0);
  glGenBuffersARB(1, &fixed_attrib_buffer_id_);

  state_.texture_units.resize(group_->max_texture_units());
  for (uint32 tt = 0; tt < state_.texture_units.size(); ++tt) {
    glActiveTexture(GL_TEXTURE0 + tt);
    // We want the last bind to be 2D.
    TextureRef* ref;
    if (features().oes_egl_image_external) {
      ref = texture_manager()->GetDefaultTextureInfo(
          GL_TEXTURE_EXTERNAL_OES);
      state_.texture_units[tt].bound_texture_external_oes = ref;
      glBindTexture(GL_TEXTURE_EXTERNAL_OES, ref ? ref->service_id() : 0);
    }
    if (features().arb_texture_rectangle) {
      ref = texture_manager()->GetDefaultTextureInfo(
          GL_TEXTURE_RECTANGLE_ARB);
      state_.texture_units[tt].bound_texture_rectangle_arb = ref;
      glBindTexture(GL_TEXTURE_RECTANGLE_ARB, ref ? ref->service_id() : 0);
    }
    ref = texture_manager()->GetDefaultTextureInfo(GL_TEXTURE_CUBE_MAP);
    state_.texture_units[tt].bound_texture_cube_map = ref;
    glBindTexture(GL_TEXTURE_CUBE_MAP, ref ? ref->service_id() : 0);
    ref = texture_manager()->GetDefaultTextureInfo(GL_TEXTURE_2D);
    state_.texture_units[tt].bound_texture_2d = ref;
    glBindTexture(GL_TEXTURE_2D, ref ? ref->service_id() : 0);
  }
  glActiveTexture(GL_TEXTURE0);
  CHECK_GL_ERROR();

  if (offscreen) {
    if (attrib_parser.samples_ > 0 && attrib_parser.sample_buffers_ > 0 &&
        features().chromium_framebuffer_multisample) {
      // Per ext_framebuffer_multisample spec, need max bound on sample count.
      // max_sample_count must be initialized to a sane value.  If
      // glGetIntegerv() throws a GL error, it leaves its argument unchanged.
      GLint max_sample_count = 1;
      glGetIntegerv(GL_MAX_SAMPLES_EXT, &max_sample_count);
      offscreen_target_samples_ = std::min(attrib_parser.samples_,
                                           max_sample_count);
    } else {
      offscreen_target_samples_ = 1;
    }
    offscreen_target_buffer_preserved_ = attrib_parser.buffer_preserved_;

    if (gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2) {
      const bool rgb8_supported =
          context_->HasExtension("GL_OES_rgb8_rgba8");
      // The only available default render buffer formats in GLES2 have very
      // little precision.  Don't enable multisampling unless 8-bit render
      // buffer formats are available--instead fall back to 8-bit textures.
      if (rgb8_supported && offscreen_target_samples_ > 1) {
        offscreen_target_color_format_ = attrib_parser.alpha_size_ > 0 ?
            GL_RGBA8 : GL_RGB8;
      } else {
        offscreen_target_samples_ = 1;
        offscreen_target_color_format_ = attrib_parser.alpha_size_ > 0 ?
            GL_RGBA : GL_RGB;
      }

      // ANGLE only supports packed depth/stencil formats, so use it if it is
      // available.
      const bool depth24_stencil8_supported =
          feature_info_->feature_flags().packed_depth24_stencil8;
      VLOG(1) << "GL_OES_packed_depth_stencil "
              << (depth24_stencil8_supported ? "" : "not ") << "supported.";
      if ((attrib_parser.depth_size_ > 0 || attrib_parser.stencil_size_ > 0) &&
          depth24_stencil8_supported) {
        offscreen_target_depth_format_ = GL_DEPTH24_STENCIL8;
        offscreen_target_stencil_format_ = 0;
      } else {
        // It may be the case that this depth/stencil combination is not
        // supported, but this will be checked later by CheckFramebufferStatus.
        offscreen_target_depth_format_ = attrib_parser.depth_size_ > 0 ?
            GL_DEPTH_COMPONENT16 : 0;
        offscreen_target_stencil_format_ = attrib_parser.stencil_size_ > 0 ?
            GL_STENCIL_INDEX8 : 0;
      }
    } else {
      offscreen_target_color_format_ = attrib_parser.alpha_size_ > 0 ?
          GL_RGBA : GL_RGB;

      // If depth is requested at all, use the packed depth stencil format if
      // it's available, as some desktop GL drivers don't support any non-packed
      // formats for depth attachments.
      const bool depth24_stencil8_supported =
          feature_info_->feature_flags().packed_depth24_stencil8;
      VLOG(1) << "GL_EXT_packed_depth_stencil "
              << (depth24_stencil8_supported ? "" : "not ") << "supported.";

      if ((attrib_parser.depth_size_ > 0 || attrib_parser.stencil_size_ > 0) &&
          depth24_stencil8_supported) {
        offscreen_target_depth_format_ = GL_DEPTH24_STENCIL8;
        offscreen_target_stencil_format_ = 0;
      } else {
        offscreen_target_depth_format_ = attrib_parser.depth_size_ > 0 ?
            GL_DEPTH_COMPONENT : 0;
        offscreen_target_stencil_format_ = attrib_parser.stencil_size_ > 0 ?
            GL_STENCIL_INDEX : 0;
      }
    }

    offscreen_saved_color_format_ = attrib_parser.alpha_size_ > 0 ?
        GL_RGBA : GL_RGB;

    // Create the target frame buffer. This is the one that the client renders
    // directly to.
    offscreen_target_frame_buffer_.reset(new BackFramebuffer(this));
    offscreen_target_frame_buffer_->Create();
    // Due to GLES2 format limitations, either the color texture (for
    // non-multisampling) or the color render buffer (for multisampling) will be
    // attached to the offscreen frame buffer.  The render buffer has more
    // limited formats available to it, but the texture can't do multisampling.
    if (IsOffscreenBufferMultisampled()) {
      offscreen_target_color_render_buffer_.reset(new BackRenderbuffer(
          renderbuffer_manager(), memory_tracker(), &state_));
      offscreen_target_color_render_buffer_->Create();
    } else {
      offscreen_target_color_texture_.reset(new BackTexture(
          memory_tracker(), &state_));
      offscreen_target_color_texture_->Create();
    }
    offscreen_target_depth_render_buffer_.reset(new BackRenderbuffer(
        renderbuffer_manager(), memory_tracker(), &state_));
    offscreen_target_depth_render_buffer_->Create();
    offscreen_target_stencil_render_buffer_.reset(new BackRenderbuffer(
        renderbuffer_manager(), memory_tracker(), &state_));
    offscreen_target_stencil_render_buffer_->Create();

    // Create the saved offscreen texture. The target frame buffer is copied
    // here when SwapBuffers is called.
    offscreen_saved_frame_buffer_.reset(new BackFramebuffer(this));
    offscreen_saved_frame_buffer_->Create();
    //
    offscreen_saved_color_texture_.reset(new BackTexture(
        memory_tracker(), &state_));
    offscreen_saved_color_texture_->Create();

    // Allocate the render buffers at their initial size and check the status
    // of the frame buffers is okay.
    if (!ResizeOffscreenFrameBuffer(size)) {
      LOG(ERROR) << "Could not allocate offscreen buffer storage.";
      Destroy(true);
      return false;
    }

    // Allocate the offscreen saved color texture.
    DCHECK(offscreen_saved_color_format_);
    offscreen_saved_color_texture_->AllocateStorage(
        gfx::Size(1, 1), offscreen_saved_color_format_, true);

    offscreen_saved_frame_buffer_->AttachRenderTexture(
        offscreen_saved_color_texture_.get());
    if (offscreen_saved_frame_buffer_->CheckStatus() !=
        GL_FRAMEBUFFER_COMPLETE) {
      LOG(ERROR) << "Offscreen saved FBO was incomplete.";
      Destroy(true);
      return false;
    }

    // Bind to the new default frame buffer (the offscreen target frame buffer).
    // This should now be associated with ID zero.
    DoBindFramebuffer(GL_FRAMEBUFFER, 0);
  } else {
    glBindFramebufferEXT(GL_FRAMEBUFFER, GetBackbufferServiceId());
    // These are NOT if the back buffer has these proprorties. They are
    // if we want the command buffer to enforce them regardless of what
    // the real backbuffer is assuming the real back buffer gives us more than
    // we ask for. In other words, if we ask for RGB and we get RGBA then we'll
    // make it appear RGB. If on the other hand we ask for RGBA nd get RGB we
    // can't do anything about that.

    GLint v = 0;
    glGetIntegerv(GL_ALPHA_BITS, &v);
    // This checks if the user requested RGBA and we have RGBA then RGBA. If the
    // user requested RGB then RGB. If the user did not specify a preference
    // than use whatever we were given. Same for DEPTH and STENCIL.
    back_buffer_color_format_ =
        (attrib_parser.alpha_size_ != 0 && v > 0) ? GL_RGBA : GL_RGB;
    glGetIntegerv(GL_DEPTH_BITS, &v);
    back_buffer_has_depth_ = attrib_parser.depth_size_ != 0 && v > 0;
    glGetIntegerv(GL_STENCIL_BITS, &v);
    back_buffer_has_stencil_ = attrib_parser.stencil_size_ != 0 && v > 0;
  }

  // OpenGL ES 2.0 implicitly enables the desktop GL capability
  // VERTEX_PROGRAM_POINT_SIZE and doesn't expose this enum. This fact
  // isn't well documented; it was discovered in the Khronos OpenGL ES
  // mailing list archives. It also implicitly enables the desktop GL
  // capability GL_POINT_SPRITE to provide access to the gl_PointCoord
  // variable in fragment shaders.
  if (gfx::GetGLImplementation() != gfx::kGLImplementationEGLGLES2) {
    glEnable(GL_VERTEX_PROGRAM_POINT_SIZE);
    glEnable(GL_POINT_SPRITE);
  }

  has_robustness_extension_ =
      context->HasExtension("GL_ARB_robustness") ||
      context->HasExtension("GL_EXT_robustness");

  if (!InitializeShaderTranslator()) {
    return false;
  }

  state_.viewport_width = size.width();
  state_.viewport_height = size.height();

  GLint viewport_params[4] = { 0 };
  glGetIntegerv(GL_MAX_VIEWPORT_DIMS, viewport_params);
  viewport_max_width_ = viewport_params[0];
  viewport_max_height_ = viewport_params[1];

  state_.scissor_width = state_.viewport_width;
  state_.scissor_height = state_.viewport_height;

  // Set all the default state because some GL drivers get it wrong.
  state_.InitCapabilities(NULL);
  state_.InitState(NULL);
  glActiveTexture(GL_TEXTURE0 + state_.active_texture_unit);

  DoBindBuffer(GL_ARRAY_BUFFER, 0);
  DoBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
  DoBindFramebuffer(GL_FRAMEBUFFER, 0);
  DoBindRenderbuffer(GL_RENDERBUFFER, 0);

  bool call_gl_clear = true;
#if defined(OS_ANDROID)
  // Temporary workaround for Android WebView because this clear ignores the
  // clip and corrupts that external UI of the App. Not calling glClear is ok
  // because the system already clears the buffer before each draw. Proper
  // fix might be setting the scissor clip properly before initialize. See
  // crbug.com/259023 for details.
  call_gl_clear = surface_->GetHandle();
#endif
  if (call_gl_clear) {
    // Clear the backbuffer.
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
  }

  supports_post_sub_buffer_ = surface->SupportsPostSubBuffer();
  if (feature_info_->workarounds()
          .disable_post_sub_buffers_for_onscreen_surfaces &&
      !surface->IsOffscreen())
    supports_post_sub_buffer_ = false;

  if (feature_info_->workarounds().reverse_point_sprite_coord_origin) {
    glPointParameteri(GL_POINT_SPRITE_COORD_ORIGIN, GL_LOWER_LEFT);
  }

  if (feature_info_->workarounds().unbind_fbo_on_context_switch) {
    context_->SetUnbindFboOnMakeCurrent();
  }

  if (feature_info_->workarounds().release_image_after_use) {
    image_manager()->SetReleaseAfterUse();
  }

  // Only compositor contexts are known to use only the subset of GL
  // that can be safely migrated between the iGPU and the dGPU. Mark
  // those contexts as safe to forcibly transition between the GPUs.
  // http://crbug.com/180876, http://crbug.com/227228
  if (!offscreen)
    context_->SetSafeToForceGpuSwitch();

  async_pixel_transfer_manager_.reset(
      AsyncPixelTransferManager::Create(context.get()));
  async_pixel_transfer_manager_->Initialize(texture_manager());

  framebuffer_manager()->AddObserver(this);

  return true;
}

Capabilities GLES2DecoderImpl::GetCapabilities() {
  DCHECK(initialized());

  Capabilities caps;

  caps.fast_npot_mo8_textures =
      feature_info_->workarounds().enable_chromium_fast_npot_mo8_textures;
  caps.egl_image_external =
      feature_info_->feature_flags().oes_egl_image_external;
  caps.texture_format_bgra8888 =
      feature_info_->feature_flags().ext_texture_format_bgra8888;
  caps.texture_format_etc1 =
      feature_info_->feature_flags().oes_compressed_etc1_rgb8_texture;
  caps.texture_rectangle = feature_info_->feature_flags().arb_texture_rectangle;
  caps.texture_usage = feature_info_->feature_flags().angle_texture_usage;
  caps.texture_storage = feature_info_->feature_flags().ext_texture_storage;
  caps.discard_framebuffer =
      feature_info_->feature_flags().ext_discard_framebuffer;
  caps.sync_query = feature_info_->feature_flags().chromium_sync_query;

#if defined(OS_MACOSX)
  // This is unconditionally true on mac, no need to test for it at runtime.
  caps.iosurface = true;
#endif

  caps.post_sub_buffer = supports_post_sub_buffer_;
  caps.map_image = !!image_manager();

  return caps;
}

void GLES2DecoderImpl::UpdateCapabilities() {
  util_.set_num_compressed_texture_formats(
      validators_->compressed_texture_format.GetValues().size());
  util_.set_num_shader_binary_formats(
      validators_->shader_binary_format.GetValues().size());
}

bool GLES2DecoderImpl::InitializeShaderTranslator() {
  TRACE_EVENT0("gpu", "GLES2DecoderImpl::InitializeShaderTranslator");

  if (!use_shader_translator_) {
    return true;
  }
  ShBuiltInResources resources;
  ShInitBuiltInResources(&resources);
  resources.MaxVertexAttribs = group_->max_vertex_attribs();
  resources.MaxVertexUniformVectors =
      group_->max_vertex_uniform_vectors();
  resources.MaxVaryingVectors = group_->max_varying_vectors();
  resources.MaxVertexTextureImageUnits =
      group_->max_vertex_texture_image_units();
  resources.MaxCombinedTextureImageUnits = group_->max_texture_units();
  resources.MaxTextureImageUnits = group_->max_texture_image_units();
  resources.MaxFragmentUniformVectors =
      group_->max_fragment_uniform_vectors();
  resources.MaxDrawBuffers = group_->max_draw_buffers();
  resources.MaxExpressionComplexity = 256;
  resources.MaxCallStackDepth = 256;

#if (ANGLE_SH_VERSION >= 110)
  GLint range[2] = { 0, 0 };
  GLint precision = 0;
  GetShaderPrecisionFormatImpl(GL_FRAGMENT_SHADER, GL_HIGH_FLOAT,
                               range, &precision);
  resources.FragmentPrecisionHigh =
      PrecisionMeetsSpecForHighpFloat(range[0], range[1], precision);
#endif

  if (force_webgl_glsl_validation_) {
    resources.OES_standard_derivatives = derivatives_explicitly_enabled_;
    resources.EXT_frag_depth = frag_depth_explicitly_enabled_;
    resources.EXT_draw_buffers = draw_buffers_explicitly_enabled_;
    if (!draw_buffers_explicitly_enabled_)
      resources.MaxDrawBuffers = 1;
#if (ANGLE_SH_VERSION >= 123)
    resources.EXT_shader_texture_lod = shader_texture_lod_explicitly_enabled_;
#endif
  } else {
    resources.OES_standard_derivatives =
        features().oes_standard_derivatives ? 1 : 0;
    resources.ARB_texture_rectangle =
        features().arb_texture_rectangle ? 1 : 0;
    resources.OES_EGL_image_external =
        features().oes_egl_image_external ? 1 : 0;
    resources.EXT_draw_buffers =
        features().ext_draw_buffers ? 1 : 0;
    resources.EXT_frag_depth =
        features().ext_frag_depth ? 1 : 0;
#if (ANGLE_SH_VERSION >= 123)
    resources.EXT_shader_texture_lod =
        features().ext_shader_texture_lod ? 1 : 0;
#endif
  }

  ShShaderSpec shader_spec = force_webgl_glsl_validation_ ? SH_WEBGL_SPEC
                                                          : SH_GLES2_SPEC;
  if (shader_spec == SH_WEBGL_SPEC && features().enable_shader_name_hashing)
#if !defined(ANGLE_SH_VERSION) || ANGLE_SH_VERSION < 108
    resources.HashFunction = &CityHashForAngle;
#else
    resources.HashFunction = &CityHash64;
#endif
  else
    resources.HashFunction = NULL;
  ShaderTranslatorInterface::GlslImplementationType implementation_type =
      gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2 ?
          ShaderTranslatorInterface::kGlslES : ShaderTranslatorInterface::kGlsl;
  int driver_bug_workarounds = 0;
  if (workarounds().needs_glsl_built_in_function_emulation)
    driver_bug_workarounds |= SH_EMULATE_BUILT_IN_FUNCTIONS;
  if (workarounds().init_gl_position_in_vertex_shader)
    driver_bug_workarounds |= SH_INIT_GL_POSITION;
  if (workarounds().unfold_short_circuit_as_ternary_operation)
    driver_bug_workarounds |= SH_UNFOLD_SHORT_CIRCUIT;
  if (workarounds().init_varyings_without_static_use)
    driver_bug_workarounds |= SH_INIT_VARYINGS_WITHOUT_STATIC_USE;
  if (workarounds().unroll_for_loop_with_sampler_array_index)
    driver_bug_workarounds |= SH_UNROLL_FOR_LOOP_WITH_SAMPLER_ARRAY_INDEX;

  vertex_translator_ = shader_translator_cache()->GetTranslator(
      SH_VERTEX_SHADER,
      shader_spec,
      &resources,
      implementation_type,
      static_cast<ShCompileOptions>(driver_bug_workarounds));
  if (!vertex_translator_.get()) {
    LOG(ERROR) << "Could not initialize vertex shader translator.";
    Destroy(true);
    return false;
  }

  fragment_translator_ = shader_translator_cache()->GetTranslator(
      SH_FRAGMENT_SHADER,
      shader_spec,
      &resources,
      implementation_type,
      static_cast<ShCompileOptions>(driver_bug_workarounds));
  if (!fragment_translator_.get()) {
    LOG(ERROR) << "Could not initialize fragment shader translator.";
    Destroy(true);
    return false;
  }
  return true;
}

bool GLES2DecoderImpl::GenBuffersHelper(GLsizei n, const GLuint* client_ids) {
  for (GLsizei ii = 0; ii < n; ++ii) {
    if (GetBuffer(client_ids[ii])) {
      return false;
    }
  }
  scoped_ptr<GLuint[]> service_ids(new GLuint[n]);
  glGenBuffersARB(n, service_ids.get());
  for (GLsizei ii = 0; ii < n; ++ii) {
    CreateBuffer(client_ids[ii], service_ids[ii]);
  }
  return true;
}

bool GLES2DecoderImpl::GenFramebuffersHelper(
    GLsizei n, const GLuint* client_ids) {
  for (GLsizei ii = 0; ii < n; ++ii) {
    if (GetFramebuffer(client_ids[ii])) {
      return false;
    }
  }
  scoped_ptr<GLuint[]> service_ids(new GLuint[n]);
  glGenFramebuffersEXT(n, service_ids.get());
  for (GLsizei ii = 0; ii < n; ++ii) {
    CreateFramebuffer(client_ids[ii], service_ids[ii]);
  }
  return true;
}

bool GLES2DecoderImpl::GenRenderbuffersHelper(
    GLsizei n, const GLuint* client_ids) {
  for (GLsizei ii = 0; ii < n; ++ii) {
    if (GetRenderbuffer(client_ids[ii])) {
      return false;
    }
  }
  scoped_ptr<GLuint[]> service_ids(new GLuint[n]);
  glGenRenderbuffersEXT(n, service_ids.get());
  for (GLsizei ii = 0; ii < n; ++ii) {
    CreateRenderbuffer(client_ids[ii], service_ids[ii]);
  }
  return true;
}

bool GLES2DecoderImpl::GenTexturesHelper(GLsizei n, const GLuint* client_ids) {
  for (GLsizei ii = 0; ii < n; ++ii) {
    if (GetTexture(client_ids[ii])) {
      return false;
    }
  }
  scoped_ptr<GLuint[]> service_ids(new GLuint[n]);
  glGenTextures(n, service_ids.get());
  for (GLsizei ii = 0; ii < n; ++ii) {
    CreateTexture(client_ids[ii], service_ids[ii]);
  }
  return true;
}

void GLES2DecoderImpl::DeleteBuffersHelper(
    GLsizei n, const GLuint* client_ids) {
  for (GLsizei ii = 0; ii < n; ++ii) {
    Buffer* buffer = GetBuffer(client_ids[ii]);
    if (buffer && !buffer->IsDeleted()) {
      state_.vertex_attrib_manager->Unbind(buffer);
      if (state_.bound_array_buffer.get() == buffer) {
        state_.bound_array_buffer = NULL;
      }
      RemoveBuffer(client_ids[ii]);
    }
  }
}

void GLES2DecoderImpl::DeleteFramebuffersHelper(
    GLsizei n, const GLuint* client_ids) {
  bool supports_separate_framebuffer_binds =
     features().chromium_framebuffer_multisample;

  for (GLsizei ii = 0; ii < n; ++ii) {
    Framebuffer* framebuffer =
        GetFramebuffer(client_ids[ii]);
    if (framebuffer && !framebuffer->IsDeleted()) {
      if (framebuffer == framebuffer_state_.bound_draw_framebuffer.get()) {
        framebuffer_state_.bound_draw_framebuffer = NULL;
        framebuffer_state_.clear_state_dirty = true;
        GLenum target = supports_separate_framebuffer_binds ?
            GL_DRAW_FRAMEBUFFER_EXT : GL_FRAMEBUFFER;
        glBindFramebufferEXT(target, GetBackbufferServiceId());
      }
      if (framebuffer == framebuffer_state_.bound_read_framebuffer.get()) {
        framebuffer_state_.bound_read_framebuffer = NULL;
        GLenum target = supports_separate_framebuffer_binds ?
            GL_READ_FRAMEBUFFER_EXT : GL_FRAMEBUFFER;
        glBindFramebufferEXT(target, GetBackbufferServiceId());
      }
      OnFboChanged();
      RemoveFramebuffer(client_ids[ii]);
    }
  }
}

void GLES2DecoderImpl::DeleteRenderbuffersHelper(
    GLsizei n, const GLuint* client_ids) {
  bool supports_separate_framebuffer_binds =
     features().chromium_framebuffer_multisample;
  for (GLsizei ii = 0; ii < n; ++ii) {
    Renderbuffer* renderbuffer =
        GetRenderbuffer(client_ids[ii]);
    if (renderbuffer && !renderbuffer->IsDeleted()) {
      if (state_.bound_renderbuffer.get() == renderbuffer) {
        state_.bound_renderbuffer = NULL;
      }
      // Unbind from current framebuffers.
      if (supports_separate_framebuffer_binds) {
        if (framebuffer_state_.bound_read_framebuffer.get()) {
          framebuffer_state_.bound_read_framebuffer
              ->UnbindRenderbuffer(GL_READ_FRAMEBUFFER_EXT, renderbuffer);
        }
        if (framebuffer_state_.bound_draw_framebuffer.get()) {
          framebuffer_state_.bound_draw_framebuffer
              ->UnbindRenderbuffer(GL_DRAW_FRAMEBUFFER_EXT, renderbuffer);
        }
      } else {
        if (framebuffer_state_.bound_draw_framebuffer.get()) {
          framebuffer_state_.bound_draw_framebuffer
              ->UnbindRenderbuffer(GL_FRAMEBUFFER, renderbuffer);
        }
      }
      framebuffer_state_.clear_state_dirty = true;
      RemoveRenderbuffer(client_ids[ii]);
    }
  }
}

void GLES2DecoderImpl::DeleteTexturesHelper(
    GLsizei n, const GLuint* client_ids) {
  bool supports_separate_framebuffer_binds =
     features().chromium_framebuffer_multisample;
  for (GLsizei ii = 0; ii < n; ++ii) {
    TextureRef* texture_ref = GetTexture(client_ids[ii]);
    if (texture_ref) {
      Texture* texture = texture_ref->texture();
      if (texture->IsAttachedToFramebuffer()) {
        framebuffer_state_.clear_state_dirty = true;
      }
      // Unbind texture_ref from texture_ref units.
      for (size_t jj = 0; jj < state_.texture_units.size(); ++jj) {
        state_.texture_units[jj].Unbind(texture_ref);
      }
      // Unbind from current framebuffers.
      if (supports_separate_framebuffer_binds) {
        if (framebuffer_state_.bound_read_framebuffer.get()) {
          framebuffer_state_.bound_read_framebuffer
              ->UnbindTexture(GL_READ_FRAMEBUFFER_EXT, texture_ref);
        }
        if (framebuffer_state_.bound_draw_framebuffer.get()) {
          framebuffer_state_.bound_draw_framebuffer
              ->UnbindTexture(GL_DRAW_FRAMEBUFFER_EXT, texture_ref);
        }
      } else {
        if (framebuffer_state_.bound_draw_framebuffer.get()) {
          framebuffer_state_.bound_draw_framebuffer
              ->UnbindTexture(GL_FRAMEBUFFER, texture_ref);
        }
      }
#if defined(OS_MACOSX)
      GLuint service_id = texture->service_id();
      if (texture->target() == GL_TEXTURE_RECTANGLE_ARB) {
        ReleaseIOSurfaceForTexture(service_id);
      }
#endif
      RemoveTexture(client_ids[ii]);
    }
  }
}

// }  // anonymous namespace

bool GLES2DecoderImpl::MakeCurrent() {
  if (!context_.get())
    return false;

  if (!context_->MakeCurrent(surface_.get()) || WasContextLost()) {
    LOG(ERROR) << "  GLES2DecoderImpl: Context lost during MakeCurrent.";

    // Some D3D drivers cannot recover from device lost in the GPU process
    // sandbox. Allow a new GPU process to launch.
    if (workarounds().exit_on_context_lost) {
      LOG(ERROR) << "Exiting GPU process because some drivers cannot reset"
                 << " a D3D device in the Chrome GPU process sandbox.";
#if defined(OS_WIN)
      base::win::SetShouldCrashOnProcessDetach(false);
#endif
      exit(0);
    }

    return false;
  }

  ProcessFinishedAsyncTransfers();

  // Rebind the FBO if it was unbound by the context.
  if (workarounds().unbind_fbo_on_context_switch)
    RestoreFramebufferBindings();

  framebuffer_state_.clear_state_dirty = true;

  return true;
}

void GLES2DecoderImpl::ProcessFinishedAsyncTransfers() {
  ProcessPendingReadPixels();
  if (engine() && query_manager_.get())
    query_manager_->ProcessPendingTransferQueries();

  // TODO(epenner): Is there a better place to do this?
  // This needs to occur before we execute any batch of commands
  // from the client, as the client may have recieved an async
  // completion while issuing those commands.
  // "DidFlushStart" would be ideal if we had such a callback.
  async_pixel_transfer_manager_->BindCompletedAsyncTransfers();
}

static void RebindCurrentFramebuffer(
    GLenum target,
    Framebuffer* framebuffer,
    GLuint back_buffer_service_id) {
  GLuint framebuffer_id = framebuffer ? framebuffer->service_id() : 0;

  if (framebuffer_id == 0) {
    framebuffer_id = back_buffer_service_id;
  }

  glBindFramebufferEXT(target, framebuffer_id);
}

void GLES2DecoderImpl::RestoreCurrentFramebufferBindings() {
  framebuffer_state_.clear_state_dirty = true;

  if (!features().chromium_framebuffer_multisample) {
    RebindCurrentFramebuffer(
        GL_FRAMEBUFFER,
        framebuffer_state_.bound_draw_framebuffer.get(),
        GetBackbufferServiceId());
  } else {
    RebindCurrentFramebuffer(
        GL_READ_FRAMEBUFFER_EXT,
        framebuffer_state_.bound_read_framebuffer.get(),
        GetBackbufferServiceId());
    RebindCurrentFramebuffer(
        GL_DRAW_FRAMEBUFFER_EXT,
        framebuffer_state_.bound_draw_framebuffer.get(),
        GetBackbufferServiceId());
  }
  OnFboChanged();
}

bool GLES2DecoderImpl::CheckFramebufferValid(
    Framebuffer* framebuffer,
    GLenum target, const char* func_name) {
  if (!framebuffer) {
    if (backbuffer_needs_clear_bits_) {
      glClearColor(0, 0, 0, (GLES2Util::GetChannelsForFormat(
          offscreen_target_color_format_) & 0x0008) != 0 ? 0 : 1);
      state_.SetDeviceColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
      glClearStencil(0);
      state_.SetDeviceStencilMaskSeparate(GL_FRONT, -1);
      state_.SetDeviceStencilMaskSeparate(GL_BACK, -1);
      glClearDepth(1.0f);
      state_.SetDeviceDepthMask(GL_TRUE);
      state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, false);
      bool reset_draw_buffer = false;
      if ((backbuffer_needs_clear_bits_ | GL_COLOR_BUFFER_BIT) != 0 &&
          group_->draw_buffer() == GL_NONE) {
        reset_draw_buffer = true;
        GLenum buf = GL_BACK;
        if (GetBackbufferServiceId() != 0)  // emulated backbuffer
          buf = GL_COLOR_ATTACHMENT0;
        glDrawBuffersARB(1, &buf);
      }
      glClear(backbuffer_needs_clear_bits_);
      if (reset_draw_buffer) {
        GLenum buf = GL_NONE;
        glDrawBuffersARB(1, &buf);
      }
      backbuffer_needs_clear_bits_ = 0;
      RestoreClearState();
    }
    return true;
  }

  if (framebuffer_manager()->IsComplete(framebuffer)) {
    return true;
  }

  GLenum completeness = framebuffer->IsPossiblyComplete();
  if (completeness != GL_FRAMEBUFFER_COMPLETE) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_FRAMEBUFFER_OPERATION, func_name, "framebuffer incomplete");
    return false;
  }

  // Are all the attachments cleared?
  if (renderbuffer_manager()->HaveUnclearedRenderbuffers() ||
      texture_manager()->HaveUnclearedMips()) {
    if (!framebuffer->IsCleared()) {
      // Can we clear them?
      if (framebuffer->GetStatus(texture_manager(), target) !=
          GL_FRAMEBUFFER_COMPLETE) {
        LOCAL_SET_GL_ERROR(
            GL_INVALID_FRAMEBUFFER_OPERATION, func_name,
            "framebuffer incomplete (clear)");
        return false;
      }
      ClearUnclearedAttachments(target, framebuffer);
    }
  }

  if (!framebuffer_manager()->IsComplete(framebuffer)) {
    if (framebuffer->GetStatus(texture_manager(), target) !=
        GL_FRAMEBUFFER_COMPLETE) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_FRAMEBUFFER_OPERATION, func_name,
          "framebuffer incomplete (check)");
      return false;
    }
    framebuffer_manager()->MarkAsComplete(framebuffer);
  }

  // NOTE: At this point we don't know if the framebuffer is complete but
  // we DO know that everything that needs to be cleared has been cleared.
  return true;
}

bool GLES2DecoderImpl::CheckBoundFramebuffersValid(const char* func_name) {
  if (!features().chromium_framebuffer_multisample) {
    bool valid = CheckFramebufferValid(
        framebuffer_state_.bound_draw_framebuffer.get(), GL_FRAMEBUFFER_EXT,
        func_name);

    if (valid)
      OnUseFramebuffer();

    return valid;
  }
  return CheckFramebufferValid(framebuffer_state_.bound_draw_framebuffer.get(),
                               GL_DRAW_FRAMEBUFFER_EXT,
                               func_name) &&
         CheckFramebufferValid(framebuffer_state_.bound_read_framebuffer.get(),
                               GL_READ_FRAMEBUFFER_EXT,
                               func_name);
}

gfx::Size GLES2DecoderImpl::GetBoundReadFrameBufferSize() {
  Framebuffer* framebuffer =
      GetFramebufferInfoForTarget(GL_READ_FRAMEBUFFER_EXT);
  if (framebuffer != NULL) {
    const Framebuffer::Attachment* attachment =
        framebuffer->GetAttachment(GL_COLOR_ATTACHMENT0);
    if (attachment) {
      return gfx::Size(attachment->width(), attachment->height());
    }
    return gfx::Size(0, 0);
  } else if (offscreen_target_frame_buffer_.get()) {
    return offscreen_size_;
  } else {
    return surface_->GetSize();
  }
}

GLenum GLES2DecoderImpl::GetBoundReadFrameBufferTextureType() {
  Framebuffer* framebuffer =
    GetFramebufferInfoForTarget(GL_READ_FRAMEBUFFER_EXT);
  if (framebuffer != NULL) {
    return framebuffer->GetColorAttachmentTextureType();
  } else {
    return GL_UNSIGNED_BYTE;
  }
}

GLenum GLES2DecoderImpl::GetBoundReadFrameBufferInternalFormat() {
  Framebuffer* framebuffer =
      GetFramebufferInfoForTarget(GL_READ_FRAMEBUFFER_EXT);
  if (framebuffer != NULL) {
    return framebuffer->GetColorAttachmentFormat();
  } else if (offscreen_target_frame_buffer_.get()) {
    return offscreen_target_color_format_;
  } else {
    return back_buffer_color_format_;
  }
}

GLenum GLES2DecoderImpl::GetBoundDrawFrameBufferInternalFormat() {
  Framebuffer* framebuffer =
      GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
  if (framebuffer != NULL) {
    return framebuffer->GetColorAttachmentFormat();
  } else if (offscreen_target_frame_buffer_.get()) {
    return offscreen_target_color_format_;
  } else {
    return back_buffer_color_format_;
  }
}

void GLES2DecoderImpl::UpdateParentTextureInfo() {
  if (!offscreen_saved_color_texture_info_.get())
    return;
  GLenum target = offscreen_saved_color_texture_info_->texture()->target();
  glBindTexture(target, offscreen_saved_color_texture_info_->service_id());
  texture_manager()->SetLevelInfo(
      offscreen_saved_color_texture_info_.get(),
      GL_TEXTURE_2D,
      0,  // level
      GL_RGBA,
      offscreen_size_.width(),
      offscreen_size_.height(),
      1,  // depth
      0,  // border
      GL_RGBA,
      GL_UNSIGNED_BYTE,
      true);
  texture_manager()->SetParameteri(
      "UpdateParentTextureInfo",
      GetErrorState(),
      offscreen_saved_color_texture_info_.get(),
      GL_TEXTURE_MAG_FILTER,
      GL_NEAREST);
  texture_manager()->SetParameteri(
      "UpdateParentTextureInfo",
      GetErrorState(),
      offscreen_saved_color_texture_info_.get(),
      GL_TEXTURE_MIN_FILTER,
      GL_NEAREST);
  texture_manager()->SetParameteri(
      "UpdateParentTextureInfo",
      GetErrorState(),
      offscreen_saved_color_texture_info_.get(),
      GL_TEXTURE_WRAP_S,
      GL_CLAMP_TO_EDGE);
  texture_manager()->SetParameteri(
      "UpdateParentTextureInfo",
      GetErrorState(),
      offscreen_saved_color_texture_info_.get(),
      GL_TEXTURE_WRAP_T,
      GL_CLAMP_TO_EDGE);
  TextureRef* texture_ref = texture_manager()->GetTextureInfoForTarget(
      &state_, target);
  glBindTexture(target, texture_ref ? texture_ref->service_id() : 0);
}

void GLES2DecoderImpl::SetResizeCallback(
    const base::Callback<void(gfx::Size, float)>& callback) {
  resize_callback_ = callback;
}

Logger* GLES2DecoderImpl::GetLogger() {
  return &logger_;
}

void GLES2DecoderImpl::BeginDecoding() {
  gpu_tracer_->BeginDecoding();
  gpu_trace_commands_ = gpu_tracer_->IsTracing();
}

void GLES2DecoderImpl::EndDecoding() {
  gpu_tracer_->EndDecoding();
}

ErrorState* GLES2DecoderImpl::GetErrorState() {
  return state_.GetErrorState();
}

void GLES2DecoderImpl::SetShaderCacheCallback(
    const ShaderCacheCallback& callback) {
  shader_cache_callback_ = callback;
}

void GLES2DecoderImpl::SetWaitSyncPointCallback(
    const WaitSyncPointCallback& callback) {
  wait_sync_point_callback_ = callback;
}

AsyncPixelTransferManager*
    GLES2DecoderImpl::GetAsyncPixelTransferManager() {
  return async_pixel_transfer_manager_.get();
}

void GLES2DecoderImpl::ResetAsyncPixelTransferManagerForTest() {
  async_pixel_transfer_manager_.reset();
}

void GLES2DecoderImpl::SetAsyncPixelTransferManagerForTest(
    AsyncPixelTransferManager* manager) {
  async_pixel_transfer_manager_ = make_scoped_ptr(manager);
}

bool GLES2DecoderImpl::GetServiceTextureId(uint32 client_texture_id,
                                           uint32* service_texture_id) {
  TextureRef* texture_ref = texture_manager()->GetTexture(client_texture_id);
  if (texture_ref) {
    *service_texture_id = texture_ref->service_id();
    return true;
  }
  return false;
}

uint32 GLES2DecoderImpl::GetTextureUploadCount() {
  return texture_state_.texture_upload_count +
         async_pixel_transfer_manager_->GetTextureUploadCount();
}

base::TimeDelta GLES2DecoderImpl::GetTotalTextureUploadTime() {
  return texture_state_.total_texture_upload_time +
         async_pixel_transfer_manager_->GetTotalTextureUploadTime();
}

base::TimeDelta GLES2DecoderImpl::GetTotalProcessingCommandsTime() {
  return total_processing_commands_time_;
}

void GLES2DecoderImpl::AddProcessingCommandsTime(base::TimeDelta time) {
  total_processing_commands_time_ += time;
}

void GLES2DecoderImpl::Destroy(bool have_context) {
  if (!initialized())
    return;

  DCHECK(!have_context || context_->IsCurrent(NULL));

  // Unbind everything.
  state_.vertex_attrib_manager = NULL;
  state_.default_vertex_attrib_manager = NULL;
  state_.texture_units.clear();
  state_.bound_array_buffer = NULL;
  state_.current_queries.clear();
  framebuffer_state_.bound_read_framebuffer = NULL;
  framebuffer_state_.bound_draw_framebuffer = NULL;
  state_.bound_renderbuffer = NULL;

  if (offscreen_saved_color_texture_info_.get()) {
    DCHECK(offscreen_target_color_texture_);
    DCHECK_EQ(offscreen_saved_color_texture_info_->service_id(),
              offscreen_saved_color_texture_->id());
    offscreen_saved_color_texture_->Invalidate();
    offscreen_saved_color_texture_info_ = NULL;
  }
  if (have_context) {
    if (copy_texture_CHROMIUM_.get()) {
      copy_texture_CHROMIUM_->Destroy();
      copy_texture_CHROMIUM_.reset();
    }

    if (state_.current_program.get()) {
      program_manager()->UnuseProgram(shader_manager(),
                                      state_.current_program.get());
    }

    if (attrib_0_buffer_id_) {
      glDeleteBuffersARB(1, &attrib_0_buffer_id_);
    }
    if (fixed_attrib_buffer_id_) {
      glDeleteBuffersARB(1, &fixed_attrib_buffer_id_);
    }

    if (validation_texture_) {
      glDeleteTextures(1, &validation_texture_);
      glDeleteFramebuffersEXT(1, &validation_fbo_multisample_);
      glDeleteFramebuffersEXT(1, &validation_fbo_);
    }

    if (offscreen_target_frame_buffer_.get())
      offscreen_target_frame_buffer_->Destroy();
    if (offscreen_target_color_texture_.get())
      offscreen_target_color_texture_->Destroy();
    if (offscreen_target_color_render_buffer_.get())
      offscreen_target_color_render_buffer_->Destroy();
    if (offscreen_target_depth_render_buffer_.get())
      offscreen_target_depth_render_buffer_->Destroy();
    if (offscreen_target_stencil_render_buffer_.get())
      offscreen_target_stencil_render_buffer_->Destroy();
    if (offscreen_saved_frame_buffer_.get())
      offscreen_saved_frame_buffer_->Destroy();
    if (offscreen_saved_color_texture_.get())
      offscreen_saved_color_texture_->Destroy();
    if (offscreen_resolved_frame_buffer_.get())
      offscreen_resolved_frame_buffer_->Destroy();
    if (offscreen_resolved_color_texture_.get())
      offscreen_resolved_color_texture_->Destroy();
  } else {
    if (offscreen_target_frame_buffer_.get())
      offscreen_target_frame_buffer_->Invalidate();
    if (offscreen_target_color_texture_.get())
      offscreen_target_color_texture_->Invalidate();
    if (offscreen_target_color_render_buffer_.get())
      offscreen_target_color_render_buffer_->Invalidate();
    if (offscreen_target_depth_render_buffer_.get())
      offscreen_target_depth_render_buffer_->Invalidate();
    if (offscreen_target_stencil_render_buffer_.get())
      offscreen_target_stencil_render_buffer_->Invalidate();
    if (offscreen_saved_frame_buffer_.get())
      offscreen_saved_frame_buffer_->Invalidate();
    if (offscreen_saved_color_texture_.get())
      offscreen_saved_color_texture_->Invalidate();
    if (offscreen_resolved_frame_buffer_.get())
      offscreen_resolved_frame_buffer_->Invalidate();
    if (offscreen_resolved_color_texture_.get())
      offscreen_resolved_color_texture_->Invalidate();
  }

  // Current program must be cleared after calling ProgramManager::UnuseProgram.
  // Otherwise, we can leak objects. http://crbug.com/258772.
  // state_.current_program must be reset before group_ is reset because
  // the later deletes the ProgramManager object that referred by
  // state_.current_program object.
  state_.current_program = NULL;

  copy_texture_CHROMIUM_.reset();

  if (query_manager_.get()) {
    query_manager_->Destroy(have_context);
    query_manager_.reset();
  }

  if (vertex_array_manager_ .get()) {
    vertex_array_manager_->Destroy(have_context);
    vertex_array_manager_.reset();
  }

  offscreen_target_frame_buffer_.reset();
  offscreen_target_color_texture_.reset();
  offscreen_target_color_render_buffer_.reset();
  offscreen_target_depth_render_buffer_.reset();
  offscreen_target_stencil_render_buffer_.reset();
  offscreen_saved_frame_buffer_.reset();
  offscreen_saved_color_texture_.reset();
  offscreen_resolved_frame_buffer_.reset();
  offscreen_resolved_color_texture_.reset();

  // Need to release these before releasing |group_| which may own the
  // ShaderTranslatorCache.
  fragment_translator_ = NULL;
  vertex_translator_ = NULL;

  // Should destroy the transfer manager before the texture manager held
  // by the context group.
  async_pixel_transfer_manager_.reset();

  if (group_.get()) {
    framebuffer_manager()->RemoveObserver(this);
    group_->Destroy(this, have_context);
    group_ = NULL;
  }

  if (context_.get()) {
    context_->ReleaseCurrent(NULL);
    context_ = NULL;
  }

#if defined(OS_MACOSX)
  for (TextureToIOSurfaceMap::iterator it = texture_to_io_surface_map_.begin();
       it != texture_to_io_surface_map_.end(); ++it) {
    CFRelease(it->second);
  }
  texture_to_io_surface_map_.clear();
#endif
}

void GLES2DecoderImpl::SetSurface(
    const scoped_refptr<gfx::GLSurface>& surface) {
  DCHECK(context_->IsCurrent(NULL));
  DCHECK(surface_.get());
  surface_ = surface;
  RestoreCurrentFramebufferBindings();
}

void GLES2DecoderImpl::ProduceFrontBuffer(const Mailbox& mailbox) {
  if (!offscreen_saved_color_texture_.get()) {
    LOG(ERROR) << "Called ProduceFrontBuffer on a non-offscreen context";
    return;
  }
  if (!offscreen_saved_color_texture_info_.get()) {
    GLuint service_id = offscreen_saved_color_texture_->id();
    offscreen_saved_color_texture_info_ = TextureRef::Create(
        texture_manager(), 0, service_id);
    texture_manager()->SetTarget(offscreen_saved_color_texture_info_.get(),
                                 GL_TEXTURE_2D);
    UpdateParentTextureInfo();
  }
  mailbox_manager()->ProduceTexture(
      GL_TEXTURE_2D, mailbox, offscreen_saved_color_texture_info_->texture());
}

bool GLES2DecoderImpl::ResizeOffscreenFrameBuffer(const gfx::Size& size) {
  bool is_offscreen = !!offscreen_target_frame_buffer_.get();
  if (!is_offscreen) {
    LOG(ERROR) << "GLES2DecoderImpl::ResizeOffscreenFrameBuffer called "
               << " with an onscreen framebuffer.";
    return false;
  }

  if (offscreen_size_ == size)
    return true;

  offscreen_size_ = size;
  int w = offscreen_size_.width();
  int h = offscreen_size_.height();
  if (w < 0 || h < 0 || h >= (INT_MAX / 4) / (w ? w : 1)) {
    LOG(ERROR) << "GLES2DecoderImpl::ResizeOffscreenFrameBuffer failed "
               << "to allocate storage due to excessive dimensions.";
    return false;
  }

  // Reallocate the offscreen target buffers.
  DCHECK(offscreen_target_color_format_);
  if (IsOffscreenBufferMultisampled()) {
    if (!offscreen_target_color_render_buffer_->AllocateStorage(
        feature_info_, offscreen_size_, offscreen_target_color_format_,
        offscreen_target_samples_)) {
      LOG(ERROR) << "GLES2DecoderImpl::ResizeOffscreenFrameBuffer failed "
                 << "to allocate storage for offscreen target color buffer.";
      return false;
    }
  } else {
    if (!offscreen_target_color_texture_->AllocateStorage(
        offscreen_size_, offscreen_target_color_format_, false)) {
      LOG(ERROR) << "GLES2DecoderImpl::ResizeOffscreenFrameBuffer failed "
                 << "to allocate storage for offscreen target color texture.";
      return false;
    }
  }
  if (offscreen_target_depth_format_ &&
      !offscreen_target_depth_render_buffer_->AllocateStorage(
      feature_info_, offscreen_size_, offscreen_target_depth_format_,
      offscreen_target_samples_)) {
    LOG(ERROR) << "GLES2DecoderImpl::ResizeOffscreenFrameBuffer failed "
               << "to allocate storage for offscreen target depth buffer.";
    return false;
  }
  if (offscreen_target_stencil_format_ &&
      !offscreen_target_stencil_render_buffer_->AllocateStorage(
      feature_info_, offscreen_size_, offscreen_target_stencil_format_,
      offscreen_target_samples_)) {
    LOG(ERROR) << "GLES2DecoderImpl::ResizeOffscreenFrameBuffer failed "
               << "to allocate storage for offscreen target stencil buffer.";
    return false;
  }

  // Attach the offscreen target buffers to the target frame buffer.
  if (IsOffscreenBufferMultisampled()) {
    offscreen_target_frame_buffer_->AttachRenderBuffer(
        GL_COLOR_ATTACHMENT0,
        offscreen_target_color_render_buffer_.get());
  } else {
    offscreen_target_frame_buffer_->AttachRenderTexture(
        offscreen_target_color_texture_.get());
  }
  if (offscreen_target_depth_format_) {
    offscreen_target_frame_buffer_->AttachRenderBuffer(
        GL_DEPTH_ATTACHMENT,
        offscreen_target_depth_render_buffer_.get());
  }
  const bool packed_depth_stencil =
      offscreen_target_depth_format_ == GL_DEPTH24_STENCIL8;
  if (packed_depth_stencil) {
    offscreen_target_frame_buffer_->AttachRenderBuffer(
        GL_STENCIL_ATTACHMENT,
        offscreen_target_depth_render_buffer_.get());
  } else if (offscreen_target_stencil_format_) {
    offscreen_target_frame_buffer_->AttachRenderBuffer(
        GL_STENCIL_ATTACHMENT,
        offscreen_target_stencil_render_buffer_.get());
  }

  if (offscreen_target_frame_buffer_->CheckStatus() !=
      GL_FRAMEBUFFER_COMPLETE) {
      LOG(ERROR) << "GLES2DecoderImpl::ResizeOffscreenFrameBuffer failed "
                 << "because offscreen FBO was incomplete.";
    return false;
  }

  // Clear the target frame buffer.
  {
    ScopedFrameBufferBinder binder(this, offscreen_target_frame_buffer_->id());
    glClearColor(0, 0, 0, (GLES2Util::GetChannelsForFormat(
        offscreen_target_color_format_) & 0x0008) != 0 ? 0 : 1);
    state_.SetDeviceColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
    glClearStencil(0);
    state_.SetDeviceStencilMaskSeparate(GL_FRONT, -1);
    state_.SetDeviceStencilMaskSeparate(GL_BACK, -1);
    glClearDepth(0);
    state_.SetDeviceDepthMask(GL_TRUE);
    state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, false);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
    RestoreClearState();
  }

  // Destroy the offscreen resolved framebuffers.
  if (offscreen_resolved_frame_buffer_.get())
    offscreen_resolved_frame_buffer_->Destroy();
  if (offscreen_resolved_color_texture_.get())
    offscreen_resolved_color_texture_->Destroy();
  offscreen_resolved_color_texture_.reset();
  offscreen_resolved_frame_buffer_.reset();

  return true;
}

error::Error GLES2DecoderImpl::HandleResizeCHROMIUM(
    uint32 immediate_data_size, const cmds::ResizeCHROMIUM& c) {
  if (!offscreen_target_frame_buffer_.get() && surface_->DeferDraws())
    return error::kDeferCommandUntilLater;

  GLuint width = static_cast<GLuint>(c.width);
  GLuint height = static_cast<GLuint>(c.height);
  GLfloat scale_factor = c.scale_factor;
  TRACE_EVENT2("gpu", "glResizeChromium", "width", width, "height", height);

  width = std::max(1U, width);
  height = std::max(1U, height);

#if defined(OS_POSIX) && !defined(OS_MACOSX) && \
    !defined(UI_COMPOSITOR_IMAGE_TRANSPORT)
  // Make sure that we are done drawing to the back buffer before resizing.
  glFinish();
#endif
  bool is_offscreen = !!offscreen_target_frame_buffer_.get();
  if (is_offscreen) {
    if (!ResizeOffscreenFrameBuffer(gfx::Size(width, height))) {
      LOG(ERROR) << "GLES2DecoderImpl: Context lost because "
                 << "ResizeOffscreenFrameBuffer failed.";
      return error::kLostContext;
    }
  }

  if (!resize_callback_.is_null()) {
    resize_callback_.Run(gfx::Size(width, height), scale_factor);
    DCHECK(context_->IsCurrent(surface_.get()));
    if (!context_->IsCurrent(surface_.get())) {
      LOG(ERROR) << "GLES2DecoderImpl: Context lost because context no longer "
                 << "current after resize callback.";
      return error::kLostContext;
    }
  }

  return error::kNoError;
}

const char* GLES2DecoderImpl::GetCommandName(unsigned int command_id) const {
  if (command_id > kStartPoint && command_id < kNumCommands) {
    return gles2::GetCommandName(static_cast<CommandId>(command_id));
  }
  return GetCommonCommandName(static_cast<cmd::CommandId>(command_id));
}

// Decode command with its arguments, and call the corresponding GL function.
// Note: args is a pointer to the command buffer. As such, it could be changed
// by a (malicious) client at any time, so if validation has to happen, it
// should operate on a copy of them.
error::Error GLES2DecoderImpl::DoCommand(
    unsigned int command,
    unsigned int arg_count,
    const void* cmd_data) {
  error::Error result = error::kNoError;
  if (log_commands()) {
    // TODO(notme): Change this to a LOG/VLOG that works in release. Tried
    // VLOG(1), no luck.
    LOG(ERROR) << "[" << logger_.GetLogPrefix() << "]" << "cmd: "
               << GetCommandName(command);
  }
  unsigned int command_index = command - kStartPoint - 1;
  if (command_index < arraysize(g_command_info)) {
    const CommandInfo& info = g_command_info[command_index];
    unsigned int info_arg_count = static_cast<unsigned int>(info.arg_count);
    if ((info.arg_flags == cmd::kFixed && arg_count == info_arg_count) ||
        (info.arg_flags == cmd::kAtLeastN && arg_count >= info_arg_count)) {
      bool doing_gpu_trace = false;
      if (gpu_trace_commands_) {
        if (CMD_FLAG_GET_TRACE_LEVEL(info.cmd_flags) <= gpu_trace_level_) {
          doing_gpu_trace = true;
          gpu_tracer_->Begin(GetCommandName(command), kTraceDecoder);
        }
      }

      uint32 immediate_data_size =
          (arg_count - info_arg_count) * sizeof(CommandBufferEntry);  // NOLINT
      switch (command) {
        #define GLES2_CMD_OP(name)                                 \
          case cmds::name::kCmdId:                                 \
            result = Handle ## name(                               \
                immediate_data_size,                               \
                *static_cast<const gles2::cmds::name*>(cmd_data)); \
            break;                                                 \

        GLES2_COMMAND_LIST(GLES2_CMD_OP)
        #undef GLES2_CMD_OP
      }

      if (doing_gpu_trace)
        gpu_tracer_->End(kTraceDecoder);

      if (debug()) {
        GLenum error;
        while ((error = glGetError()) != GL_NO_ERROR) {
          LOG(ERROR) << "[" << logger_.GetLogPrefix() << "] "
                     << "GL ERROR: " << GLES2Util::GetStringEnum(error) << " : "
                     << GetCommandName(command);
          LOCAL_SET_GL_ERROR(error, "DoCommand", "GL error from driver");
        }
      }
    } else {
      result = error::kInvalidArguments;
    }
  } else {
    result = DoCommonCommand(command, arg_count, cmd_data);
  }
  if (result == error::kNoError && current_decoder_error_ != error::kNoError) {
      result = current_decoder_error_;
      current_decoder_error_ = error::kNoError;
  }
  return result;
}

void GLES2DecoderImpl::RemoveBuffer(GLuint client_id) {
  buffer_manager()->RemoveBuffer(client_id);
}

bool GLES2DecoderImpl::CreateProgramHelper(GLuint client_id) {
  if (GetProgram(client_id)) {
    return false;
  }
  GLuint service_id = glCreateProgram();
  if (service_id != 0) {
    CreateProgram(client_id, service_id);
  }
  return true;
}

bool GLES2DecoderImpl::CreateShaderHelper(GLenum type, GLuint client_id) {
  if (GetShader(client_id)) {
    return false;
  }
  GLuint service_id = glCreateShader(type);
  if (service_id != 0) {
    CreateShader(client_id, service_id, type);
  }
  return true;
}

void GLES2DecoderImpl::DoFinish() {
  glFinish();
  ProcessPendingReadPixels();
  ProcessPendingQueries();
}

void GLES2DecoderImpl::DoFlush() {
  glFlush();
  ProcessPendingQueries();
}

void GLES2DecoderImpl::DoActiveTexture(GLenum texture_unit) {
  GLuint texture_index = texture_unit - GL_TEXTURE0;
  if (texture_index >= state_.texture_units.size()) {
    LOCAL_SET_GL_ERROR_INVALID_ENUM(
        "glActiveTexture", texture_unit, "texture_unit");
    return;
  }
  state_.active_texture_unit = texture_index;
  glActiveTexture(texture_unit);
}

void GLES2DecoderImpl::DoBindBuffer(GLenum target, GLuint client_id) {
  Buffer* buffer = NULL;
  GLuint service_id = 0;
  if (client_id != 0) {
    buffer = GetBuffer(client_id);
    if (!buffer) {
      if (!group_->bind_generates_resource()) {
        LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
                           "glBindBuffer",
                           "id not generated by glGenBuffers");
        return;
      }

      // It's a new id so make a buffer buffer for it.
      glGenBuffersARB(1, &service_id);
      CreateBuffer(client_id, service_id);
      buffer = GetBuffer(client_id);
      IdAllocatorInterface* id_allocator =
          group_->GetIdAllocator(id_namespaces::kBuffers);
      id_allocator->MarkAsUsed(client_id);
    }
  }
  LogClientServiceForInfo(buffer, client_id, "glBindBuffer");
  if (buffer) {
    if (!buffer_manager()->SetTarget(buffer, target)) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_OPERATION,
          "glBindBuffer", "buffer bound to more than 1 target");
      return;
    }
    service_id = buffer->service_id();
  }
  switch (target) {
    case GL_ARRAY_BUFFER:
      state_.bound_array_buffer = buffer;
      break;
    case GL_ELEMENT_ARRAY_BUFFER:
      state_.vertex_attrib_manager->SetElementArrayBuffer(buffer);
      break;
    default:
      NOTREACHED();  // Validation should prevent us getting here.
      break;
  }
  glBindBuffer(target, service_id);
}

bool GLES2DecoderImpl::BoundFramebufferHasColorAttachmentWithAlpha(
    bool all_draw_buffers) {
  Framebuffer* framebuffer =
      GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
  if (!all_draw_buffers || !framebuffer) {
    return (GLES2Util::GetChannelsForFormat(
        GetBoundDrawFrameBufferInternalFormat()) & 0x0008) != 0;
  }
  return framebuffer->HasAlphaMRT();
}

bool GLES2DecoderImpl::BoundFramebufferHasDepthAttachment() {
  Framebuffer* framebuffer =
      GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
  if (framebuffer) {
    return framebuffer->HasDepthAttachment();
  }
  if (offscreen_target_frame_buffer_.get()) {
    return offscreen_target_depth_format_ != 0;
  }
  return back_buffer_has_depth_;
}

bool GLES2DecoderImpl::BoundFramebufferHasStencilAttachment() {
  Framebuffer* framebuffer =
      GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
  if (framebuffer) {
    return framebuffer->HasStencilAttachment();
  }
  if (offscreen_target_frame_buffer_.get()) {
    return offscreen_target_stencil_format_ != 0 ||
           offscreen_target_depth_format_ == GL_DEPTH24_STENCIL8;
  }
  return back_buffer_has_stencil_;
}

void GLES2DecoderImpl::ApplyDirtyState() {
  if (framebuffer_state_.clear_state_dirty) {
    bool have_alpha = BoundFramebufferHasColorAttachmentWithAlpha(true);
    state_.SetDeviceColorMask(state_.color_mask_red,
                              state_.color_mask_green,
                              state_.color_mask_blue,
                              state_.color_mask_alpha && have_alpha);

    bool have_depth = BoundFramebufferHasDepthAttachment();
    state_.SetDeviceDepthMask(state_.depth_mask && have_depth);

    bool have_stencil = BoundFramebufferHasStencilAttachment();
    state_.SetDeviceStencilMaskSeparate(
        GL_FRONT, have_stencil ? state_.stencil_front_writemask : 0);
    state_.SetDeviceStencilMaskSeparate(
        GL_BACK, have_stencil ? state_.stencil_back_writemask : 0);

    state_.SetDeviceCapabilityState(
        GL_DEPTH_TEST, state_.enable_flags.depth_test && have_depth);
    state_.SetDeviceCapabilityState(
        GL_STENCIL_TEST, state_.enable_flags.stencil_test && have_stencil);
    framebuffer_state_.clear_state_dirty = false;
  }
}

GLuint GLES2DecoderImpl::GetBackbufferServiceId() const {
  return (offscreen_target_frame_buffer_.get())
             ? offscreen_target_frame_buffer_->id()
             : (surface_.get() ? surface_->GetBackingFrameBufferObject() : 0);
}

void GLES2DecoderImpl::RestoreState(const ContextState* prev_state) const {
  TRACE_EVENT1("gpu", "GLES2DecoderImpl::RestoreState",
               "context", logger_.GetLogPrefix());
  // Restore the Framebuffer first because of bugs in Intel drivers.
  // Intel drivers incorrectly clip the viewport settings to
  // the size of the current framebuffer object.
  RestoreFramebufferBindings();
  state_.RestoreState(prev_state);
}

void GLES2DecoderImpl::RestoreFramebufferBindings() const {
  GLuint service_id =
      framebuffer_state_.bound_draw_framebuffer.get()
          ? framebuffer_state_.bound_draw_framebuffer->service_id()
          : GetBackbufferServiceId();
  if (!features().chromium_framebuffer_multisample) {
    glBindFramebufferEXT(GL_FRAMEBUFFER, service_id);
  } else {
    glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER, service_id);
    service_id = framebuffer_state_.bound_read_framebuffer.get()
                     ? framebuffer_state_.bound_read_framebuffer->service_id()
                     : GetBackbufferServiceId();
    glBindFramebufferEXT(GL_READ_FRAMEBUFFER, service_id);
  }
  OnFboChanged();
}

void GLES2DecoderImpl::RestoreTextureState(unsigned service_id) const {
  Texture* texture = texture_manager()->GetTextureForServiceId(service_id);
  if (texture) {
    GLenum target = texture->target();
    glBindTexture(target, service_id);
    glTexParameteri(
        target, GL_TEXTURE_WRAP_S, texture->wrap_s());
    glTexParameteri(
        target, GL_TEXTURE_WRAP_T, texture->wrap_t());
    glTexParameteri(
        target, GL_TEXTURE_MIN_FILTER, texture->min_filter());
    glTexParameteri(
        target, GL_TEXTURE_MAG_FILTER, texture->mag_filter());
    RestoreTextureUnitBindings(state_.active_texture_unit);
  }
}

void GLES2DecoderImpl::ClearAllAttributes() const {
  // Must use native VAO 0, as RestoreAllAttributes can't fully restore
  // other VAOs.
  if (feature_info_->feature_flags().native_vertex_array_object)
    glBindVertexArrayOES(0);

  for (uint32 i = 0; i < group_->max_vertex_attribs(); ++i) {
    if (i != 0) // Never disable attribute 0
      glDisableVertexAttribArray(i);
    if(features().angle_instanced_arrays)
      glVertexAttribDivisorANGLE(i, 0);
  }
}

void GLES2DecoderImpl::RestoreAllAttributes() const {
  state_.RestoreVertexAttribs();
}

void GLES2DecoderImpl::SetIgnoreCachedStateForTest(bool ignore) {
  state_.SetIgnoreCachedStateForTest(ignore);
}

void GLES2DecoderImpl::OnFboChanged() const {
  if (workarounds().restore_scissor_on_fbo_change)
    state_.fbo_binding_for_scissor_workaround_dirty_ = true;
}

// Called after the FBO is checked for completeness.
void GLES2DecoderImpl::OnUseFramebuffer() const {
  if (state_.fbo_binding_for_scissor_workaround_dirty_) {
    state_.fbo_binding_for_scissor_workaround_dirty_ = false;
    // The driver forgets the correct scissor when modifying the FBO binding.
    glScissor(state_.scissor_x,
              state_.scissor_y,
              state_.scissor_width,
              state_.scissor_height);

    // crbug.com/222018 - Also on QualComm, the flush here avoids flicker,
    // it's unclear how this bug works.
    glFlush();
  }
}

void GLES2DecoderImpl::DoBindFramebuffer(GLenum target, GLuint client_id) {
  Framebuffer* framebuffer = NULL;
  GLuint service_id = 0;
  if (client_id != 0) {
    framebuffer = GetFramebuffer(client_id);
    if (!framebuffer) {
      if (!group_->bind_generates_resource()) {
        LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
                           "glBindFramebuffer",
                           "id not generated by glGenFramebuffers");
        return;
      }

      // It's a new id so make a framebuffer framebuffer for it.
      glGenFramebuffersEXT(1, &service_id);
      CreateFramebuffer(client_id, service_id);
      framebuffer = GetFramebuffer(client_id);
      IdAllocatorInterface* id_allocator =
          group_->GetIdAllocator(id_namespaces::kFramebuffers);
      id_allocator->MarkAsUsed(client_id);
    } else {
      service_id = framebuffer->service_id();
    }
    framebuffer->MarkAsValid();
  }
  LogClientServiceForInfo(framebuffer, client_id, "glBindFramebuffer");

  if (target == GL_FRAMEBUFFER || target == GL_DRAW_FRAMEBUFFER_EXT) {
    framebuffer_state_.bound_draw_framebuffer = framebuffer;
  }

  // vmiura: This looks like dup code
  if (target == GL_FRAMEBUFFER || target == GL_READ_FRAMEBUFFER_EXT) {
    framebuffer_state_.bound_read_framebuffer = framebuffer;
  }

  framebuffer_state_.clear_state_dirty = true;

  // If we are rendering to the backbuffer get the FBO id for any simulated
  // backbuffer.
  if (framebuffer == NULL) {
    service_id = GetBackbufferServiceId();
  }

  glBindFramebufferEXT(target, service_id);
  OnFboChanged();
}

void GLES2DecoderImpl::DoBindRenderbuffer(GLenum target, GLuint client_id) {
  Renderbuffer* renderbuffer = NULL;
  GLuint service_id = 0;
  if (client_id != 0) {
    renderbuffer = GetRenderbuffer(client_id);
    if (!renderbuffer) {
      if (!group_->bind_generates_resource()) {
        LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
                           "glBindRenderbuffer",
                           "id not generated by glGenRenderbuffers");
        return;
      }

      // It's a new id so make a renderbuffer renderbuffer for it.
      glGenRenderbuffersEXT(1, &service_id);
      CreateRenderbuffer(client_id, service_id);
      renderbuffer = GetRenderbuffer(client_id);
      IdAllocatorInterface* id_allocator =
          group_->GetIdAllocator(id_namespaces::kRenderbuffers);
      id_allocator->MarkAsUsed(client_id);
    } else {
      service_id = renderbuffer->service_id();
    }
    renderbuffer->MarkAsValid();
  }
  LogClientServiceForInfo(renderbuffer, client_id, "glBindRenderbuffer");
  state_.bound_renderbuffer = renderbuffer;
  glBindRenderbufferEXT(target, service_id);
}

void GLES2DecoderImpl::DoBindTexture(GLenum target, GLuint client_id) {
  TextureRef* texture_ref = NULL;
  GLuint service_id = 0;
  if (client_id != 0) {
    texture_ref = GetTexture(client_id);
    if (!texture_ref) {
      if (!group_->bind_generates_resource()) {
        LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
                           "glBindTexture",
                           "id not generated by glGenTextures");
        return;
      }

      // It's a new id so make a texture texture for it.
      glGenTextures(1, &service_id);
      DCHECK_NE(0u, service_id);
      CreateTexture(client_id, service_id);
      texture_ref = GetTexture(client_id);
      IdAllocatorInterface* id_allocator =
          group_->GetIdAllocator(id_namespaces::kTextures);
      id_allocator->MarkAsUsed(client_id);
    }
  } else {
    texture_ref = texture_manager()->GetDefaultTextureInfo(target);
  }

  // Check the texture exists
  if (texture_ref) {
    Texture* texture = texture_ref->texture();
    // Check that we are not trying to bind it to a different target.
    if (texture->target() != 0 && texture->target() != target) {
      LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
                         "glBindTexture",
                         "texture bound to more than 1 target.");
      return;
    }
    LogClientServiceForInfo(texture, client_id, "glBindTexture");
    if (texture->target() == 0) {
      texture_manager()->SetTarget(texture_ref, target);
    }
    glBindTexture(target, texture->service_id());
  } else {
    glBindTexture(target, 0);
  }

  TextureUnit& unit = state_.texture_units[state_.active_texture_unit];
  unit.bind_target = target;
  switch (target) {
    case GL_TEXTURE_2D:
      unit.bound_texture_2d = texture_ref;
      break;
    case GL_TEXTURE_CUBE_MAP:
      unit.bound_texture_cube_map = texture_ref;
      break;
    case GL_TEXTURE_EXTERNAL_OES:
      unit.bound_texture_external_oes = texture_ref;
      break;
    case GL_TEXTURE_RECTANGLE_ARB:
      unit.bound_texture_rectangle_arb = texture_ref;
      break;
    default:
      NOTREACHED();  // Validation should prevent us getting here.
      break;
  }
}

void GLES2DecoderImpl::DoDisableVertexAttribArray(GLuint index) {
  if (state_.vertex_attrib_manager->Enable(index, false)) {
    if (index != 0 ||
        gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2) {
      glDisableVertexAttribArray(index);
    }
  } else {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE,
        "glDisableVertexAttribArray", "index out of range");
  }
}

void GLES2DecoderImpl::DoDiscardFramebufferEXT(GLenum target,
                                               GLsizei numAttachments,
                                               const GLenum* attachments) {
  Framebuffer* framebuffer =
      GetFramebufferInfoForTarget(GL_FRAMEBUFFER);

  // Validates the attachments. If one of them fails
  // the whole command fails.
  for (GLsizei i = 0; i < numAttachments; ++i) {
    if ((framebuffer &&
        !validators_->attachment.IsValid(attachments[i])) ||
       (!framebuffer &&
        !validators_->backbuffer_attachment.IsValid(attachments[i]))) {
      LOCAL_SET_GL_ERROR_INVALID_ENUM(
          "glDiscardFramebufferEXT", attachments[i], "attachments");
      return;
    }
  }

  // Marks each one of them as not cleared
  for (GLsizei i = 0; i < numAttachments; ++i) {
    if (framebuffer) {
      framebuffer->MarkAttachmentAsCleared(renderbuffer_manager(),
                                           texture_manager(),
                                           attachments[i],
                                           false);
    } else {
      switch (attachments[i]) {
        case GL_COLOR_EXT:
          backbuffer_needs_clear_bits_ |= GL_COLOR_BUFFER_BIT;
          break;
        case GL_DEPTH_EXT:
          backbuffer_needs_clear_bits_ |= GL_DEPTH_BUFFER_BIT;
        case GL_STENCIL_EXT:
          backbuffer_needs_clear_bits_ |= GL_STENCIL_BUFFER_BIT;
          break;
        default:
          NOTREACHED();
          break;
      }
    }
  }

  // If the default framebuffer is bound but we are still rendering to an
  // FBO, translate attachment names that refer to default framebuffer
  // channels to corresponding framebuffer attachments.
  scoped_ptr<GLenum[]> translated_attachments(new GLenum[numAttachments]);
  for (GLsizei i = 0; i < numAttachments; ++i) {
    GLenum attachment = attachments[i];
    if (!framebuffer && GetBackbufferServiceId()) {
      switch (attachment) {
        case GL_COLOR_EXT:
          attachment = GL_COLOR_ATTACHMENT0;
          break;
        case GL_DEPTH_EXT:
          attachment = GL_DEPTH_ATTACHMENT;
          break;
        case GL_STENCIL_EXT:
          attachment = GL_STENCIL_ATTACHMENT;
          break;
        default:
          NOTREACHED();
          return;
      }
    }
    translated_attachments[i] = attachment;
  }

  ScopedRenderTo do_render(framebuffer);
  glDiscardFramebufferEXT(target, numAttachments, translated_attachments.get());
}

void GLES2DecoderImpl::DoEnableVertexAttribArray(GLuint index) {
  if (state_.vertex_attrib_manager->Enable(index, true)) {
    glEnableVertexAttribArray(index);
  } else {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glEnableVertexAttribArray", "index out of range");
  }
}

void GLES2DecoderImpl::DoGenerateMipmap(GLenum target) {
  TextureRef* texture_ref = texture_manager()->GetTextureInfoForTarget(
      &state_, target);
  if (!texture_ref ||
      !texture_manager()->CanGenerateMipmaps(texture_ref)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, "glGenerateMipmap", "Can not generate mips");
    return;
  }

  if (target == GL_TEXTURE_CUBE_MAP) {
    for (int i = 0; i < 6; ++i) {
      GLenum face = GL_TEXTURE_CUBE_MAP_POSITIVE_X + i;
      if (!texture_manager()->ClearTextureLevel(this, texture_ref, face, 0)) {
        LOCAL_SET_GL_ERROR(
            GL_OUT_OF_MEMORY, "glGenerateMipmap", "dimensions too big");
        return;
      }
    }
  } else {
    if (!texture_manager()->ClearTextureLevel(this, texture_ref, target, 0)) {
      LOCAL_SET_GL_ERROR(
          GL_OUT_OF_MEMORY, "glGenerateMipmap", "dimensions too big");
      return;
    }
  }

  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER("glGenerateMipmap");
  // Workaround for Mac driver bug. In the large scheme of things setting
  // glTexParamter twice for glGenerateMipmap is probably not a lage performance
  // hit so there's probably no need to make this conditional. The bug appears
  // to be that if the filtering mode is set to something that doesn't require
  // mipmaps for rendering, or is never set to something other than the default,
  // then glGenerateMipmap misbehaves.
  if (workarounds().set_texture_filter_before_generating_mipmap) {
    glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEAREST);
  }
  glGenerateMipmapEXT(target);
  if (workarounds().set_texture_filter_before_generating_mipmap) {
    glTexParameteri(target, GL_TEXTURE_MIN_FILTER,
                    texture_ref->texture()->min_filter());
  }
  GLenum error = LOCAL_PEEK_GL_ERROR("glGenerateMipmap");
  if (error == GL_NO_ERROR) {
    texture_manager()->MarkMipmapsGenerated(texture_ref);
  }
}

bool GLES2DecoderImpl::GetHelper(
    GLenum pname, GLint* params, GLsizei* num_written) {
  DCHECK(num_written);
  if (gfx::GetGLImplementation() != gfx::kGLImplementationEGLGLES2) {
    switch (pname) {
      case GL_IMPLEMENTATION_COLOR_READ_FORMAT:
        *num_written = 1;
        // Return the GL implementation's preferred format and (see below type)
        // if we have the GL extension that exposes this. This allows the GPU
        // client to use the implementation's preferred format for glReadPixels
        // for optimisation.
        //
        // A conflicting extension (GL_ARB_ES2_compatibility) specifies an error
        // case when requested on integer/floating point buffers but which is
        // acceptable on GLES2 and with the GL_OES_read_format extension.
        //
        // Therefore if an error occurs we swallow the error and use the
        // internal implementation.
        if (params) {
          if (context_->HasExtension("GL_OES_read_format")) {
            ScopedGLErrorSuppressor suppressor("GLES2DecoderImpl::GetHelper",
                                               GetErrorState());
            glGetIntegerv(pname, params);
            if (glGetError() == GL_NO_ERROR)
              return true;
          }
          *params = GLES2Util::GetPreferredGLReadPixelsFormat(
              GetBoundReadFrameBufferInternalFormat());
        }
        return true;
      case GL_IMPLEMENTATION_COLOR_READ_TYPE:
        *num_written = 1;
        if (params) {
          if (context_->HasExtension("GL_OES_read_format")) {
            ScopedGLErrorSuppressor suppressor("GLES2DecoderImpl::GetHelper",
                                               GetErrorState());
            glGetIntegerv(pname, params);
            if (glGetError() == GL_NO_ERROR)
              return true;
          }
          *params = GLES2Util::GetPreferredGLReadPixelsType(
              GetBoundReadFrameBufferInternalFormat(),
              GetBoundReadFrameBufferTextureType());
        }
        return true;
      case GL_MAX_FRAGMENT_UNIFORM_VECTORS:
        *num_written = 1;
        if (params) {
          *params = group_->max_fragment_uniform_vectors();
        }
        return true;
      case GL_MAX_VARYING_VECTORS:
        *num_written = 1;
        if (params) {
          *params = group_->max_varying_vectors();
        }
        return true;
      case GL_MAX_VERTEX_UNIFORM_VECTORS:
        *num_written = 1;
        if (params) {
          *params = group_->max_vertex_uniform_vectors();
        }
        return true;
      }
  }
  switch (pname) {
    case GL_MAX_VIEWPORT_DIMS:
      if (offscreen_target_frame_buffer_.get()) {
        *num_written = 2;
        if (params) {
          params[0] = renderbuffer_manager()->max_renderbuffer_size();
          params[1] = renderbuffer_manager()->max_renderbuffer_size();
        }
        return true;
      }
      return false;
    case GL_MAX_SAMPLES:
      *num_written = 1;
      if (params) {
        params[0] = renderbuffer_manager()->max_samples();
      }
      return true;
    case GL_MAX_RENDERBUFFER_SIZE:
      *num_written = 1;
      if (params) {
        params[0] = renderbuffer_manager()->max_renderbuffer_size();
      }
      return true;
    case GL_MAX_TEXTURE_SIZE:
      *num_written = 1;
      if (params) {
        params[0] = texture_manager()->MaxSizeForTarget(GL_TEXTURE_2D);
      }
      return true;
    case GL_MAX_CUBE_MAP_TEXTURE_SIZE:
      *num_written = 1;
      if (params) {
        params[0] = texture_manager()->MaxSizeForTarget(GL_TEXTURE_CUBE_MAP);
      }
      return true;
    case GL_MAX_COLOR_ATTACHMENTS_EXT:
      *num_written = 1;
      if (params) {
        params[0] = group_->max_color_attachments();
      }
      return true;
    case GL_MAX_DRAW_BUFFERS_ARB:
      *num_written = 1;
      if (params) {
        params[0] = group_->max_draw_buffers();
      }
      return true;
    case GL_ALPHA_BITS:
      *num_written = 1;
      if (params) {
        GLint v = 0;
        glGetIntegerv(GL_ALPHA_BITS, &v);
        params[0] = BoundFramebufferHasColorAttachmentWithAlpha(false) ? v : 0;
      }
      return true;
    case GL_DEPTH_BITS:
      *num_written = 1;
      if (params) {
        GLint v = 0;
        glGetIntegerv(GL_DEPTH_BITS, &v);
        params[0] = BoundFramebufferHasDepthAttachment() ? v : 0;
      }
      return true;
    case GL_STENCIL_BITS:
      *num_written = 1;
      if (params) {
        GLint v = 0;
        glGetIntegerv(GL_STENCIL_BITS, &v);
        params[0] = BoundFramebufferHasStencilAttachment() ? v : 0;
      }
      return true;
    case GL_COMPRESSED_TEXTURE_FORMATS:
      *num_written = validators_->compressed_texture_format.GetValues().size();
      if (params) {
        for (GLint ii = 0; ii < *num_written; ++ii) {
          params[ii] = validators_->compressed_texture_format.GetValues()[ii];
        }
      }
      return true;
    case GL_NUM_COMPRESSED_TEXTURE_FORMATS:
      *num_written = 1;
      if (params) {
        *params = validators_->compressed_texture_format.GetValues().size();
      }
      return true;
    case GL_NUM_SHADER_BINARY_FORMATS:
      *num_written = 1;
      if (params) {
        *params = validators_->shader_binary_format.GetValues().size();
      }
      return true;
    case GL_SHADER_BINARY_FORMATS:
      *num_written = validators_->shader_binary_format.GetValues().size();
      if (params) {
        for (GLint ii = 0; ii <  *num_written; ++ii) {
          params[ii] = validators_->shader_binary_format.GetValues()[ii];
        }
      }
      return true;
    case GL_SHADER_COMPILER:
      *num_written = 1;
      if (params) {
        *params = GL_TRUE;
      }
      return true;
    case GL_ARRAY_BUFFER_BINDING:
      *num_written = 1;
      if (params) {
        if (state_.bound_array_buffer.get()) {
          GLuint client_id = 0;
          buffer_manager()->GetClientId(state_.bound_array_buffer->service_id(),
                                        &client_id);
          *params = client_id;
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_ELEMENT_ARRAY_BUFFER_BINDING:
      *num_written = 1;
      if (params) {
        if (state_.vertex_attrib_manager->element_array_buffer()) {
          GLuint client_id = 0;
          buffer_manager()->GetClientId(
              state_.vertex_attrib_manager->element_array_buffer()->
                  service_id(), &client_id);
          *params = client_id;
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_FRAMEBUFFER_BINDING:
    // case GL_DRAW_FRAMEBUFFER_BINDING_EXT: (same as GL_FRAMEBUFFER_BINDING)
      *num_written = 1;
      if (params) {
        Framebuffer* framebuffer =
            GetFramebufferInfoForTarget(GL_FRAMEBUFFER);
        if (framebuffer) {
          GLuint client_id = 0;
          framebuffer_manager()->GetClientId(
              framebuffer->service_id(), &client_id);
          *params = client_id;
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_READ_FRAMEBUFFER_BINDING_EXT:
      *num_written = 1;
      if (params) {
        Framebuffer* framebuffer =
            GetFramebufferInfoForTarget(GL_READ_FRAMEBUFFER_EXT);
        if (framebuffer) {
          GLuint client_id = 0;
          framebuffer_manager()->GetClientId(
              framebuffer->service_id(), &client_id);
          *params = client_id;
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_RENDERBUFFER_BINDING:
      *num_written = 1;
      if (params) {
        Renderbuffer* renderbuffer =
            GetRenderbufferInfoForTarget(GL_RENDERBUFFER);
        if (renderbuffer) {
          *params = renderbuffer->client_id();
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_CURRENT_PROGRAM:
      *num_written = 1;
      if (params) {
        if (state_.current_program.get()) {
          GLuint client_id = 0;
          program_manager()->GetClientId(
              state_.current_program->service_id(), &client_id);
          *params = client_id;
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_VERTEX_ARRAY_BINDING_OES:
      *num_written = 1;
      if (params) {
        if (state_.vertex_attrib_manager.get() !=
            state_.default_vertex_attrib_manager.get()) {
          GLuint client_id = 0;
          vertex_array_manager_->GetClientId(
              state_.vertex_attrib_manager->service_id(), &client_id);
          *params = client_id;
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_TEXTURE_BINDING_2D:
      *num_written = 1;
      if (params) {
        TextureUnit& unit = state_.texture_units[state_.active_texture_unit];
        if (unit.bound_texture_2d.get()) {
          *params = unit.bound_texture_2d->client_id();
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_TEXTURE_BINDING_CUBE_MAP:
      *num_written = 1;
      if (params) {
        TextureUnit& unit = state_.texture_units[state_.active_texture_unit];
        if (unit.bound_texture_cube_map.get()) {
          *params = unit.bound_texture_cube_map->client_id();
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_TEXTURE_BINDING_EXTERNAL_OES:
      *num_written = 1;
      if (params) {
        TextureUnit& unit = state_.texture_units[state_.active_texture_unit];
        if (unit.bound_texture_external_oes.get()) {
          *params = unit.bound_texture_external_oes->client_id();
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_TEXTURE_BINDING_RECTANGLE_ARB:
      *num_written = 1;
      if (params) {
        TextureUnit& unit = state_.texture_units[state_.active_texture_unit];
        if (unit.bound_texture_rectangle_arb.get()) {
          *params = unit.bound_texture_rectangle_arb->client_id();
        } else {
          *params = 0;
        }
      }
      return true;
    case GL_UNPACK_FLIP_Y_CHROMIUM:
      *num_written = 1;
      if (params) {
        params[0] = unpack_flip_y_;
      }
      return true;
    case GL_UNPACK_PREMULTIPLY_ALPHA_CHROMIUM:
      *num_written = 1;
      if (params) {
        params[0] = unpack_premultiply_alpha_;
      }
      return true;
    case GL_UNPACK_UNPREMULTIPLY_ALPHA_CHROMIUM:
      *num_written = 1;
      if (params) {
        params[0] = unpack_unpremultiply_alpha_;
      }
      return true;
    case GL_BIND_GENERATES_RESOURCE_CHROMIUM:
      *num_written = 1;
      if (params) {
        params[0] = group_->bind_generates_resource() ? 1 : 0;
      }
      return true;
    default:
      if (pname >= GL_DRAW_BUFFER0_ARB &&
          pname < GL_DRAW_BUFFER0_ARB + group_->max_draw_buffers()) {
        *num_written = 1;
        if (params) {
          Framebuffer* framebuffer =
              GetFramebufferInfoForTarget(GL_FRAMEBUFFER);
          if (framebuffer) {
            params[0] = framebuffer->GetDrawBuffer(pname);
          } else {  // backbuffer
            if (pname == GL_DRAW_BUFFER0_ARB)
              params[0] = group_->draw_buffer();
            else
              params[0] = GL_NONE;
          }
        }
        return true;
      }
      *num_written = util_.GLGetNumValuesReturned(pname);
      return false;
  }
}

bool GLES2DecoderImpl::GetNumValuesReturnedForGLGet(
    GLenum pname, GLsizei* num_values) {
  if (state_.GetStateAsGLint(pname, NULL, num_values)) {
    return true;
  }
  return GetHelper(pname, NULL, num_values);
}

GLenum GLES2DecoderImpl::AdjustGetPname(GLenum pname) {
  if (GL_MAX_SAMPLES == pname &&
      features().use_img_for_multisampled_render_to_texture) {
    return GL_MAX_SAMPLES_IMG;
  }
  return pname;
}

void GLES2DecoderImpl::DoGetBooleanv(GLenum pname, GLboolean* params) {
  DCHECK(params);
  GLsizei num_written = 0;
  if (GetNumValuesReturnedForGLGet(pname, &num_written)) {
    scoped_ptr<GLint[]> values(new GLint[num_written]);
    if (!state_.GetStateAsGLint(pname, values.get(), &num_written)) {
      GetHelper(pname, values.get(), &num_written);
    }
    for (GLsizei ii = 0; ii < num_written; ++ii) {
      params[ii] = static_cast<GLboolean>(values[ii]);
    }
  } else {
    pname = AdjustGetPname(pname);
    glGetBooleanv(pname, params);
  }
}

void GLES2DecoderImpl::DoGetFloatv(GLenum pname, GLfloat* params) {
  DCHECK(params);
  GLsizei num_written = 0;
  if (!state_.GetStateAsGLfloat(pname, params, &num_written)) {
    if (GetHelper(pname, NULL, &num_written)) {
      scoped_ptr<GLint[]> values(new GLint[num_written]);
      GetHelper(pname, values.get(), &num_written);
      for (GLsizei ii = 0; ii < num_written; ++ii) {
        params[ii] = static_cast<GLfloat>(values[ii]);
      }
    } else {
      pname = AdjustGetPname(pname);
      glGetFloatv(pname, params);
    }
  }
}

void GLES2DecoderImpl::DoGetIntegerv(GLenum pname, GLint* params) {
  DCHECK(params);
  GLsizei num_written;
  if (!state_.GetStateAsGLint(pname, params, &num_written) &&
      !GetHelper(pname, params, &num_written)) {
    pname = AdjustGetPname(pname);
    glGetIntegerv(pname, params);
  }
}

void GLES2DecoderImpl::DoGetProgramiv(
    GLuint program_id, GLenum pname, GLint* params) {
  Program* program = GetProgramInfoNotShader(program_id, "glGetProgramiv");
  if (!program) {
    return;
  }
  program->GetProgramiv(pname, params);
}

void GLES2DecoderImpl::DoGetBufferParameteriv(
    GLenum target, GLenum pname, GLint* params) {
  // Just delegate it. Some validation is actually done before this.
  buffer_manager()->ValidateAndDoGetBufferParameteriv(
      &state_, target, pname, params);
}

void GLES2DecoderImpl::DoBindAttribLocation(
    GLuint program_id, GLuint index, const char* name) {
  if (!StringIsValidForGLES(name)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glBindAttribLocation", "Invalid character");
    return;
  }
  if (ProgramManager::IsInvalidPrefix(name, strlen(name))) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, "glBindAttribLocation", "reserved prefix");
    return;
  }
  if (index >= group_->max_vertex_attribs()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glBindAttribLocation", "index out of range");
    return;
  }
  Program* program = GetProgramInfoNotShader(
      program_id, "glBindAttribLocation");
  if (!program) {
    return;
  }
  program->SetAttribLocationBinding(name, static_cast<GLint>(index));
  glBindAttribLocation(program->service_id(), index, name);
}

error::Error GLES2DecoderImpl::HandleBindAttribLocationBucket(
    uint32 immediate_data_size, const cmds::BindAttribLocationBucket& c) {
  GLuint program = static_cast<GLuint>(c.program);
  GLuint index = static_cast<GLuint>(c.index);
  Bucket* bucket = GetBucket(c.name_bucket_id);
  if (!bucket || bucket->size() == 0) {
    return error::kInvalidArguments;
  }
  std::string name_str;
  if (!bucket->GetAsString(&name_str)) {
    return error::kInvalidArguments;
  }
  DoBindAttribLocation(program, index, name_str.c_str());
  return error::kNoError;
}

void GLES2DecoderImpl::DoBindUniformLocationCHROMIUM(
    GLuint program_id, GLint location, const char* name) {
  if (!StringIsValidForGLES(name)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE,
        "glBindUniformLocationCHROMIUM", "Invalid character");
    return;
  }
  if (ProgramManager::IsInvalidPrefix(name, strlen(name))) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glBindUniformLocationCHROMIUM", "reserved prefix");
    return;
  }
  if (location < 0 || static_cast<uint32>(location) >=
      (group_->max_fragment_uniform_vectors() +
       group_->max_vertex_uniform_vectors()) * 4) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE,
        "glBindUniformLocationCHROMIUM", "location out of range");
    return;
  }
  Program* program = GetProgramInfoNotShader(
      program_id, "glBindUniformLocationCHROMIUM");
  if (!program) {
    return;
  }
  if (!program->SetUniformLocationBinding(name, location)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE,
        "glBindUniformLocationCHROMIUM", "location out of range");
  }
}

error::Error GLES2DecoderImpl::HandleBindUniformLocationCHROMIUMBucket(
    uint32 immediate_data_size,
    const cmds::BindUniformLocationCHROMIUMBucket& c) {
  GLuint program = static_cast<GLuint>(c.program);
  GLint location = static_cast<GLint>(c.location);
  Bucket* bucket = GetBucket(c.name_bucket_id);
  if (!bucket || bucket->size() == 0) {
    return error::kInvalidArguments;
  }
  std::string name_str;
  if (!bucket->GetAsString(&name_str)) {
    return error::kInvalidArguments;
  }
  DoBindUniformLocationCHROMIUM(program, location, name_str.c_str());
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleDeleteShader(
    uint32 immediate_data_size, const cmds::DeleteShader& c) {
  GLuint client_id = c.shader;
  if (client_id) {
    Shader* shader = GetShader(client_id);
    if (shader) {
      if (!shader->IsDeleted()) {
        glDeleteShader(shader->service_id());
        shader_manager()->MarkAsDeleted(shader);
      }
    } else {
      LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "glDeleteShader", "unknown shader");
    }
  }
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleDeleteProgram(
    uint32 immediate_data_size, const cmds::DeleteProgram& c) {
  GLuint client_id = c.program;
  if (client_id) {
    Program* program = GetProgram(client_id);
    if (program) {
      if (!program->IsDeleted()) {
        program_manager()->MarkAsDeleted(shader_manager(), program);
      }
    } else {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_VALUE, "glDeleteProgram", "unknown program");
    }
  }
  return error::kNoError;
}

void GLES2DecoderImpl::DoDeleteSharedIdsCHROMIUM(
    GLuint namespace_id, GLsizei n, const GLuint* ids) {
  IdAllocatorInterface* id_allocator = group_->GetIdAllocator(namespace_id);
  for (GLsizei ii = 0; ii < n; ++ii) {
    id_allocator->FreeID(ids[ii]);
  }
}

error::Error GLES2DecoderImpl::HandleDeleteSharedIdsCHROMIUM(
    uint32 immediate_data_size, const cmds::DeleteSharedIdsCHROMIUM& c) {
  GLuint namespace_id = static_cast<GLuint>(c.namespace_id);
  GLsizei n = static_cast<GLsizei>(c.n);
  uint32 data_size;
  if (!SafeMultiplyUint32(n, sizeof(GLuint), &data_size)) {
    return error::kOutOfBounds;
  }
  const GLuint* ids = GetSharedMemoryAs<const GLuint*>(
      c.ids_shm_id, c.ids_shm_offset, data_size);
  if (n < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "DeleteSharedIdsCHROMIUM", "n < 0");
    return error::kNoError;
  }
  if (ids == NULL) {
    return error::kOutOfBounds;
  }
  DoDeleteSharedIdsCHROMIUM(namespace_id, n, ids);
  return error::kNoError;
}

void GLES2DecoderImpl::DoGenSharedIdsCHROMIUM(
    GLuint namespace_id, GLuint id_offset, GLsizei n, GLuint* ids) {
  IdAllocatorInterface* id_allocator = group_->GetIdAllocator(namespace_id);
  if (id_offset == 0) {
    for (GLsizei ii = 0; ii < n; ++ii) {
      ids[ii] = id_allocator->AllocateID();
    }
  } else {
    for (GLsizei ii = 0; ii < n; ++ii) {
      ids[ii] = id_allocator->AllocateIDAtOrAbove(id_offset);
      id_offset = ids[ii] + 1;
    }
  }
}

error::Error GLES2DecoderImpl::HandleGenSharedIdsCHROMIUM(
    uint32 immediate_data_size, const cmds::GenSharedIdsCHROMIUM& c) {
  GLuint namespace_id = static_cast<GLuint>(c.namespace_id);
  GLuint id_offset = static_cast<GLuint>(c.id_offset);
  GLsizei n = static_cast<GLsizei>(c.n);
  uint32 data_size;
  if (!SafeMultiplyUint32(n, sizeof(GLuint), &data_size)) {
    return error::kOutOfBounds;
  }
  GLuint* ids = GetSharedMemoryAs<GLuint*>(
      c.ids_shm_id, c.ids_shm_offset, data_size);
  if (n < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "GenSharedIdsCHROMIUM", "n < 0");
    return error::kNoError;
  }
  if (ids == NULL) {
    return error::kOutOfBounds;
  }
  DoGenSharedIdsCHROMIUM(namespace_id, id_offset, n, ids);
  return error::kNoError;
}

void GLES2DecoderImpl::DoRegisterSharedIdsCHROMIUM(
    GLuint namespace_id, GLsizei n, const GLuint* ids) {
  IdAllocatorInterface* id_allocator = group_->GetIdAllocator(namespace_id);
  for (GLsizei ii = 0; ii < n; ++ii) {
    if (!id_allocator->MarkAsUsed(ids[ii])) {
      for (GLsizei jj = 0; jj < ii; ++jj) {
        id_allocator->FreeID(ids[jj]);
      }
      LOCAL_SET_GL_ERROR(
          GL_INVALID_VALUE, "RegisterSharedIdsCHROMIUM",
          "attempt to register id that already exists");
      return;
    }
  }
}

error::Error GLES2DecoderImpl::HandleRegisterSharedIdsCHROMIUM(
    uint32 immediate_data_size, const cmds::RegisterSharedIdsCHROMIUM& c) {
  GLuint namespace_id = static_cast<GLuint>(c.namespace_id);
  GLsizei n = static_cast<GLsizei>(c.n);
  uint32 data_size;
  if (!SafeMultiplyUint32(n, sizeof(GLuint), &data_size)) {
    return error::kOutOfBounds;
  }
  GLuint* ids = GetSharedMemoryAs<GLuint*>(
      c.ids_shm_id, c.ids_shm_offset, data_size);
  if (n < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "RegisterSharedIdsCHROMIUM", "n < 0");
    return error::kNoError;
  }
  if (ids == NULL) {
    return error::kOutOfBounds;
  }
  DoRegisterSharedIdsCHROMIUM(namespace_id, n, ids);
  return error::kNoError;
}

error::Error GLES2DecoderImpl::DoClear(GLbitfield mask) {
  DCHECK(!ShouldDeferDraws());
  if (CheckBoundFramebuffersValid("glClear")) {
    ApplyDirtyState();
    ScopedRenderTo do_render(framebuffer_state_.bound_draw_framebuffer.get());
    glClear(mask);
  }
  return error::kNoError;
}

void GLES2DecoderImpl::DoFramebufferRenderbuffer(
    GLenum target, GLenum attachment, GLenum renderbuffertarget,
    GLuint client_renderbuffer_id) {
  Framebuffer* framebuffer = GetFramebufferInfoForTarget(target);
  if (!framebuffer) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glFramebufferRenderbuffer", "no framebuffer bound");
    return;
  }
  GLuint service_id = 0;
  Renderbuffer* renderbuffer = NULL;
  if (client_renderbuffer_id) {
    renderbuffer = GetRenderbuffer(client_renderbuffer_id);
    if (!renderbuffer) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_OPERATION,
          "glFramebufferRenderbuffer", "unknown renderbuffer");
      return;
    }
    service_id = renderbuffer->service_id();
  }
  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER("glFramebufferRenderbuffer");
  glFramebufferRenderbufferEXT(
      target, attachment, renderbuffertarget, service_id);
  GLenum error = LOCAL_PEEK_GL_ERROR("glFramebufferRenderbuffer");
  if (error == GL_NO_ERROR) {
    framebuffer->AttachRenderbuffer(attachment, renderbuffer);
  }
  if (framebuffer == framebuffer_state_.bound_draw_framebuffer.get()) {
    framebuffer_state_.clear_state_dirty = true;
  }
  OnFboChanged();
}

void GLES2DecoderImpl::DoDisable(GLenum cap) {
  if (SetCapabilityState(cap, false)) {
    glDisable(cap);
  }
}

void GLES2DecoderImpl::DoEnable(GLenum cap) {
  if (SetCapabilityState(cap, true)) {
    glEnable(cap);
  }
}

void GLES2DecoderImpl::DoDepthRangef(GLclampf znear, GLclampf zfar) {
  state_.z_near = std::min(1.0f, std::max(0.0f, znear));
  state_.z_far = std::min(1.0f, std::max(0.0f, zfar));
  glDepthRange(znear, zfar);
}

void GLES2DecoderImpl::DoSampleCoverage(GLclampf value, GLboolean invert) {
  state_.sample_coverage_value = std::min(1.0f, std::max(0.0f, value));
  state_.sample_coverage_invert = (invert != 0);
  glSampleCoverage(state_.sample_coverage_value, invert);
}

// Assumes framebuffer is complete.
void GLES2DecoderImpl::ClearUnclearedAttachments(
    GLenum target, Framebuffer* framebuffer) {
  if (target == GL_READ_FRAMEBUFFER_EXT) {
    // bind this to the DRAW point, clear then bind back to READ
    // TODO(gman): I don't think there is any guarantee that an FBO that
    //   is complete on the READ attachment will be complete as a DRAW
    //   attachment.
    glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, 0);
    glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, framebuffer->service_id());
  }
  GLbitfield clear_bits = 0;
  if (framebuffer->HasUnclearedColorAttachments()) {
    glClearColor(
        0.0f, 0.0f, 0.0f,
        (GLES2Util::GetChannelsForFormat(
             framebuffer->GetColorAttachmentFormat()) & 0x0008) != 0 ? 0.0f :
                                                                       1.0f);
    state_.SetDeviceColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
    clear_bits |= GL_COLOR_BUFFER_BIT;
    if (feature_info_->feature_flags().ext_draw_buffers)
      framebuffer->PrepareDrawBuffersForClear();
  }

  if (framebuffer->HasUnclearedAttachment(GL_STENCIL_ATTACHMENT) ||
      framebuffer->HasUnclearedAttachment(GL_DEPTH_STENCIL_ATTACHMENT)) {
    glClearStencil(0);
    state_.SetDeviceStencilMaskSeparate(GL_FRONT, -1);
    state_.SetDeviceStencilMaskSeparate(GL_BACK, -1);
    clear_bits |= GL_STENCIL_BUFFER_BIT;
  }

  if (framebuffer->HasUnclearedAttachment(GL_DEPTH_ATTACHMENT) ||
      framebuffer->HasUnclearedAttachment(GL_DEPTH_STENCIL_ATTACHMENT)) {
    glClearDepth(1.0f);
    state_.SetDeviceDepthMask(GL_TRUE);
    clear_bits |= GL_DEPTH_BUFFER_BIT;
  }

  state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, false);
  glClear(clear_bits);

  if ((clear_bits | GL_COLOR_BUFFER_BIT) != 0 &&
      feature_info_->feature_flags().ext_draw_buffers)
    framebuffer->RestoreDrawBuffersAfterClear();

  framebuffer_manager()->MarkAttachmentsAsCleared(
      framebuffer, renderbuffer_manager(), texture_manager());

  RestoreClearState();

  if (target == GL_READ_FRAMEBUFFER_EXT) {
    glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, framebuffer->service_id());
    Framebuffer* draw_framebuffer =
        GetFramebufferInfoForTarget(GL_DRAW_FRAMEBUFFER_EXT);
    GLuint service_id = draw_framebuffer ? draw_framebuffer->service_id() :
                                           GetBackbufferServiceId();
    glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, service_id);
  }
}

void GLES2DecoderImpl::RestoreClearState() {
  framebuffer_state_.clear_state_dirty = true;
  glClearColor(
      state_.color_clear_red, state_.color_clear_green, state_.color_clear_blue,
      state_.color_clear_alpha);
  glClearStencil(state_.stencil_clear);
  glClearDepth(state_.depth_clear);
  if (state_.enable_flags.scissor_test) {
    state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, true);
  }
}

GLenum GLES2DecoderImpl::DoCheckFramebufferStatus(GLenum target) {
  Framebuffer* framebuffer =
      GetFramebufferInfoForTarget(target);
  if (!framebuffer) {
    return GL_FRAMEBUFFER_COMPLETE;
  }
  GLenum completeness = framebuffer->IsPossiblyComplete();
  if (completeness != GL_FRAMEBUFFER_COMPLETE) {
    return completeness;
  }
  return framebuffer->GetStatus(texture_manager(), target);
}

void GLES2DecoderImpl::DoFramebufferTexture2D(
    GLenum target, GLenum attachment, GLenum textarget,
    GLuint client_texture_id, GLint level) {
  DoFramebufferTexture2DCommon(
    "glFramebufferTexture2D", target, attachment,
    textarget, client_texture_id, level, 0);
}

void GLES2DecoderImpl::DoFramebufferTexture2DMultisample(
    GLenum target, GLenum attachment, GLenum textarget,
    GLuint client_texture_id, GLint level, GLsizei samples) {
  DoFramebufferTexture2DCommon(
    "glFramebufferTexture2DMultisample", target, attachment,
    textarget, client_texture_id, level, samples);
}

void GLES2DecoderImpl::DoFramebufferTexture2DCommon(
    const char* name, GLenum target, GLenum attachment, GLenum textarget,
    GLuint client_texture_id, GLint level, GLsizei samples) {
  if (samples > renderbuffer_manager()->max_samples()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE,
        "glFramebufferTexture2DMultisample", "samples too large");
    return;
  }
  Framebuffer* framebuffer = GetFramebufferInfoForTarget(target);
  if (!framebuffer) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        name, "no framebuffer bound.");
    return;
  }
  GLuint service_id = 0;
  TextureRef* texture_ref = NULL;
  if (client_texture_id) {
    texture_ref = GetTexture(client_texture_id);
    if (!texture_ref) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_OPERATION,
          name, "unknown texture_ref");
      return;
    }
    service_id = texture_ref->service_id();
  }

  if (!texture_manager()->ValidForTarget(textarget, level, 0, 0, 1)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE,
        name, "level out of range");
    return;
  }

  if (texture_ref)
    DoWillUseTexImageIfNeeded(texture_ref->texture(), textarget);

  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER(name);
  if (0 == samples) {
    glFramebufferTexture2DEXT(target, attachment, textarget, service_id, level);
  } else {
    if (features().use_img_for_multisampled_render_to_texture) {
      glFramebufferTexture2DMultisampleIMG(target, attachment, textarget,
          service_id, level, samples);
    } else {
      glFramebufferTexture2DMultisampleEXT(target, attachment, textarget,
          service_id, level, samples);
    }
  }
  GLenum error = LOCAL_PEEK_GL_ERROR(name);
  if (error == GL_NO_ERROR) {
    framebuffer->AttachTexture(attachment, texture_ref, textarget, level,
         samples);
  }
  if (framebuffer == framebuffer_state_.bound_draw_framebuffer.get()) {
    framebuffer_state_.clear_state_dirty = true;
  }

  if (texture_ref)
    DoDidUseTexImageIfNeeded(texture_ref->texture(), textarget);

  OnFboChanged();
}

void GLES2DecoderImpl::DoGetFramebufferAttachmentParameteriv(
    GLenum target, GLenum attachment, GLenum pname, GLint* params) {
  Framebuffer* framebuffer = GetFramebufferInfoForTarget(target);
  if (!framebuffer) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glGetFramebufferAttachmentParameteriv", "no framebuffer bound");
    return;
  }
  if (pname == GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME) {
    const Framebuffer::Attachment* attachment_object =
        framebuffer->GetAttachment(attachment);
    *params = attachment_object ? attachment_object->object_name() : 0;
  } else {
    if (pname == GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_SAMPLES_EXT &&
        features().use_img_for_multisampled_render_to_texture) {
      pname = GL_TEXTURE_SAMPLES_IMG;
    }
    glGetFramebufferAttachmentParameterivEXT(target, attachment, pname, params);
  }
}

void GLES2DecoderImpl::DoGetRenderbufferParameteriv(
    GLenum target, GLenum pname, GLint* params) {
  Renderbuffer* renderbuffer =
      GetRenderbufferInfoForTarget(GL_RENDERBUFFER);
  if (!renderbuffer) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glGetRenderbufferParameteriv", "no renderbuffer bound");
    return;
  }
  switch (pname) {
    case GL_RENDERBUFFER_INTERNAL_FORMAT:
      *params = renderbuffer->internal_format();
      break;
    case GL_RENDERBUFFER_WIDTH:
      *params = renderbuffer->width();
      break;
    case GL_RENDERBUFFER_HEIGHT:
      *params = renderbuffer->height();
      break;
    case GL_RENDERBUFFER_SAMPLES_EXT:
      if (features().use_img_for_multisampled_render_to_texture) {
        glGetRenderbufferParameterivEXT(target, GL_RENDERBUFFER_SAMPLES_IMG,
            params);
      } else {
        glGetRenderbufferParameterivEXT(target, GL_RENDERBUFFER_SAMPLES_EXT,
            params);
      }
    default:
      glGetRenderbufferParameterivEXT(target, pname, params);
      break;
  }
}

void GLES2DecoderImpl::DoBlitFramebufferCHROMIUM(
    GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1,
    GLint dstX0, GLint dstY0, GLint dstX1, GLint dstY1,
    GLbitfield mask, GLenum filter) {
  DCHECK(!ShouldDeferReads() && !ShouldDeferDraws());

  if (!CheckBoundFramebuffersValid("glBlitFramebufferCHROMIUM")) {
    return;
  }

  state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, false);
  ScopedRenderTo do_render(framebuffer_state_.bound_draw_framebuffer.get());
  BlitFramebufferHelper(
      srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, mask, filter);
  state_.SetDeviceCapabilityState(GL_SCISSOR_TEST,
                                  state_.enable_flags.scissor_test);
}

void GLES2DecoderImpl::RenderbufferStorageMultisampleHelper(
    const FeatureInfo* feature_info,
    GLenum target,
    GLsizei samples,
    GLenum internal_format,
    GLsizei width,
    GLsizei height) {
  // TODO(sievers): This could be resolved at the GL binding level, but the
  // binding process is currently a bit too 'brute force'.
  if (feature_info->feature_flags().is_angle) {
    glRenderbufferStorageMultisampleANGLE(
        target, samples, internal_format, width, height);
  } else if (feature_info->feature_flags().use_core_framebuffer_multisample) {
    glRenderbufferStorageMultisample(
        target, samples, internal_format, width, height);
  } else {
    glRenderbufferStorageMultisampleEXT(
        target, samples, internal_format, width, height);
  }
}

void GLES2DecoderImpl::BlitFramebufferHelper(GLint srcX0,
                                             GLint srcY0,
                                             GLint srcX1,
                                             GLint srcY1,
                                             GLint dstX0,
                                             GLint dstY0,
                                             GLint dstX1,
                                             GLint dstY1,
                                             GLbitfield mask,
                                             GLenum filter) {
  // TODO(sievers): This could be resolved at the GL binding level, but the
  // binding process is currently a bit too 'brute force'.
  if (feature_info_->feature_flags().is_angle) {
    glBlitFramebufferANGLE(
        srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, mask, filter);
  } else if (feature_info_->feature_flags().use_core_framebuffer_multisample) {
    glBlitFramebuffer(
        srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, mask, filter);
  } else {
    glBlitFramebufferEXT(
        srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, mask, filter);
  }
}

bool GLES2DecoderImpl::ValidateRenderbufferStorageMultisample(
    GLsizei samples,
    GLenum internalformat,
    GLsizei width,
    GLsizei height) {
  if (samples > renderbuffer_manager()->max_samples()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE,
        "glRenderbufferStorageMultisample", "samples too large");
    return false;
  }

  if (width > renderbuffer_manager()->max_renderbuffer_size() ||
      height > renderbuffer_manager()->max_renderbuffer_size()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE,
        "glRenderbufferStorageMultisample", "dimensions too large");
    return false;
  }

  uint32 estimated_size = 0;
  if (!renderbuffer_manager()->ComputeEstimatedRenderbufferSize(
           width, height, samples, internalformat, &estimated_size)) {
    LOCAL_SET_GL_ERROR(
        GL_OUT_OF_MEMORY,
        "glRenderbufferStorageMultisample", "dimensions too large");
    return false;
  }

  if (!EnsureGPUMemoryAvailable(estimated_size)) {
    LOCAL_SET_GL_ERROR(
        GL_OUT_OF_MEMORY,
        "glRenderbufferStorageMultisample", "out of memory");
    return false;
  }

  return true;
}

void GLES2DecoderImpl::DoRenderbufferStorageMultisampleCHROMIUM(
    GLenum target, GLsizei samples, GLenum internalformat,
    GLsizei width, GLsizei height) {
  Renderbuffer* renderbuffer = GetRenderbufferInfoForTarget(GL_RENDERBUFFER);
  if (!renderbuffer) {
    LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
                       "glRenderbufferStorageMultisampleCHROMIUM",
                       "no renderbuffer bound");
    return;
  }

  if (!ValidateRenderbufferStorageMultisample(
      samples, internalformat, width, height)) {
    return;
  }

  GLenum impl_format =
      renderbuffer_manager()->InternalRenderbufferFormatToImplFormat(
          internalformat);
  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER(
      "glRenderbufferStorageMultisampleCHROMIUM");
  RenderbufferStorageMultisampleHelper(
      feature_info_, target, samples, impl_format, width, height);
  GLenum error =
      LOCAL_PEEK_GL_ERROR("glRenderbufferStorageMultisampleCHROMIUM");
  if (error == GL_NO_ERROR) {

    if (workarounds().validate_multisample_buffer_allocation) {
      if (!VerifyMultisampleRenderbufferIntegrity(
          renderbuffer->service_id(), impl_format)) {
        LOCAL_SET_GL_ERROR(
            GL_OUT_OF_MEMORY,
            "glRenderbufferStorageMultisampleCHROMIUM", "out of memory");
        return;
      }
    }

    // TODO(gman): If renderbuffers tracked which framebuffers they were
    // attached to we could just mark those framebuffers as not complete.
    framebuffer_manager()->IncFramebufferStateChangeCount();
    renderbuffer_manager()->SetInfo(
        renderbuffer, samples, internalformat, width, height);
  }
}

// This is the handler for multisampled_render_to_texture extensions.
void GLES2DecoderImpl::DoRenderbufferStorageMultisampleEXT(
    GLenum target, GLsizei samples, GLenum internalformat,
    GLsizei width, GLsizei height) {
  Renderbuffer* renderbuffer = GetRenderbufferInfoForTarget(GL_RENDERBUFFER);
  if (!renderbuffer) {
    LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
                       "glRenderbufferStorageMultisampleEXT",
                       "no renderbuffer bound");
    return;
  }

  if (!ValidateRenderbufferStorageMultisample(
      samples, internalformat, width, height)) {
    return;
  }

  GLenum impl_format =
      renderbuffer_manager()->InternalRenderbufferFormatToImplFormat(
          internalformat);
  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER("glRenderbufferStorageMultisampleEXT");
  if (features().use_img_for_multisampled_render_to_texture) {
    glRenderbufferStorageMultisampleIMG(
        target, samples, impl_format, width, height);
  } else {
    glRenderbufferStorageMultisampleEXT(
        target, samples, impl_format, width, height);
  }
  GLenum error = LOCAL_PEEK_GL_ERROR("glRenderbufferStorageMultisampleEXT");
  if (error == GL_NO_ERROR) {
    // TODO(gman): If renderbuffers tracked which framebuffers they were
    // attached to we could just mark those framebuffers as not complete.
    framebuffer_manager()->IncFramebufferStateChangeCount();
    renderbuffer_manager()->SetInfo(
        renderbuffer, samples, internalformat, width, height);
  }
}

// This function validates the allocation of a multisampled renderbuffer
// by clearing it to a key color, blitting the contents to a texture, and
// reading back the color to ensure it matches the key.
bool GLES2DecoderImpl::VerifyMultisampleRenderbufferIntegrity(
    GLuint renderbuffer, GLenum format) {

  // Only validate color buffers.
  // These formats have been selected because they are very common or are known
  // to be used by the WebGL backbuffer. If problems are observed with other
  // color formats they can be added here.
  switch(format) {
    case GL_RGB:
    case GL_RGB8:
    case GL_RGBA:
    case GL_RGBA8:
      break;
    default:
      return true;
  }

  GLint draw_framebuffer, read_framebuffer;

  // Cache framebuffer and texture bindings.
  glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &draw_framebuffer);
  glGetIntegerv(GL_READ_FRAMEBUFFER_BINDING, &read_framebuffer);

  if (!validation_texture_) {
    GLint bound_texture;
    glGetIntegerv(GL_TEXTURE_BINDING_2D, &bound_texture);

    // Create additional resources needed for the verification.
    glGenTextures(1, &validation_texture_);
    glGenFramebuffersEXT(1, &validation_fbo_multisample_);
    glGenFramebuffersEXT(1, &validation_fbo_);

    // Texture only needs to be 1x1.
    glBindTexture(GL_TEXTURE_2D, validation_texture_);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 1, 1, 0, GL_RGB,
        GL_UNSIGNED_BYTE, NULL);

    glBindFramebufferEXT(GL_FRAMEBUFFER, validation_fbo_);
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
        GL_TEXTURE_2D, validation_texture_, 0);

    glBindTexture(GL_TEXTURE_2D, bound_texture);
  }

  glBindFramebufferEXT(GL_FRAMEBUFFER, validation_fbo_multisample_);
  glFramebufferRenderbufferEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
      GL_RENDERBUFFER, renderbuffer);

  // Cache current state and reset it to the values we require.
  GLboolean scissor_enabled = false;
  glGetBooleanv(GL_SCISSOR_TEST, &scissor_enabled);
  if (scissor_enabled)
    state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, false);

  GLboolean color_mask[4] = {GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE};
  glGetBooleanv(GL_COLOR_WRITEMASK, color_mask);
  state_.SetDeviceColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);

  GLfloat clear_color[4] = {0.0f, 0.0f, 0.0f, 0.0f};
  glGetFloatv(GL_COLOR_CLEAR_VALUE, clear_color);
  glClearColor(1.0f, 0.0f, 1.0f, 1.0f);

  // Clear the buffer to the desired key color.
  glClear(GL_COLOR_BUFFER_BIT);

  // Blit from the multisample buffer to a standard texture.
  glBindFramebufferEXT(GL_READ_FRAMEBUFFER, validation_fbo_multisample_);
  glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER, validation_fbo_);

  BlitFramebufferHelper(
      0, 0, 1, 1, 0, 0, 1, 1, GL_COLOR_BUFFER_BIT, GL_NEAREST);

  // Read a pixel from the buffer.
  glBindFramebufferEXT(GL_FRAMEBUFFER, validation_fbo_);

  unsigned char pixel[3] = {0, 0, 0};
  glReadPixels(0, 0, 1, 1, GL_RGB, GL_UNSIGNED_BYTE, &pixel);

  // Detach the renderbuffer.
  glBindFramebufferEXT(GL_FRAMEBUFFER, validation_fbo_multisample_);
  glFramebufferRenderbufferEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
      GL_RENDERBUFFER, 0);

  // Restore cached state.
  if (scissor_enabled)
    state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, true);

  state_.SetDeviceColorMask(
      color_mask[0], color_mask[1], color_mask[2], color_mask[3]);
  glClearColor(clear_color[0], clear_color[1], clear_color[2], clear_color[3]);
  glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER, draw_framebuffer);
  glBindFramebufferEXT(GL_READ_FRAMEBUFFER, read_framebuffer);

  // Return true if the pixel matched the desired key color.
  return (pixel[0] == 0xFF &&
      pixel[1] == 0x00 &&
      pixel[2] == 0xFF);
}

void GLES2DecoderImpl::DoRenderbufferStorage(
  GLenum target, GLenum internalformat, GLsizei width, GLsizei height) {
  Renderbuffer* renderbuffer =
      GetRenderbufferInfoForTarget(GL_RENDERBUFFER);
  if (!renderbuffer) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glRenderbufferStorage", "no renderbuffer bound");
    return;
  }

  if (width > renderbuffer_manager()->max_renderbuffer_size() ||
      height > renderbuffer_manager()->max_renderbuffer_size()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glRenderbufferStorage", "dimensions too large");
    return;
  }

  uint32 estimated_size = 0;
  if (!renderbuffer_manager()->ComputeEstimatedRenderbufferSize(
           width, height, 1, internalformat, &estimated_size)) {
    LOCAL_SET_GL_ERROR(
        GL_OUT_OF_MEMORY, "glRenderbufferStorage", "dimensions too large");
    return;
  }

  if (!EnsureGPUMemoryAvailable(estimated_size)) {
    LOCAL_SET_GL_ERROR(
        GL_OUT_OF_MEMORY, "glRenderbufferStorage", "out of memory");
    return;
  }

  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER("glRenderbufferStorage");
  glRenderbufferStorageEXT(
      target,
      renderbuffer_manager()->InternalRenderbufferFormatToImplFormat(
          internalformat),
      width,
      height);
  GLenum error = LOCAL_PEEK_GL_ERROR("glRenderbufferStorage");
  if (error == GL_NO_ERROR) {
    // TODO(gman): If tetxures tracked which framebuffers they were attached to
    // we could just mark those framebuffers as not complete.
    framebuffer_manager()->IncFramebufferStateChangeCount();
    renderbuffer_manager()->SetInfo(
        renderbuffer, 1, internalformat, width, height);
  }
}

void GLES2DecoderImpl::DoLinkProgram(GLuint program_id) {
  TRACE_EVENT0("gpu", "GLES2DecoderImpl::DoLinkProgram");
  Program* program = GetProgramInfoNotShader(
      program_id, "glLinkProgram");
  if (!program) {
    return;
  }

  LogClientServiceForInfo(program, program_id, "glLinkProgram");
  ShaderTranslator* vertex_translator = NULL;
  ShaderTranslator* fragment_translator = NULL;
  if (use_shader_translator_) {
    vertex_translator = vertex_translator_.get();
    fragment_translator = fragment_translator_.get();
  }
  if (program->Link(shader_manager(),
                    vertex_translator,
                    fragment_translator,
                    workarounds().count_all_in_varyings_packing ?
                        Program::kCountAll : Program::kCountOnlyStaticallyUsed,
                    shader_cache_callback_)) {
    if (program == state_.current_program.get()) {
      if (workarounds().use_current_program_after_successful_link)
        glUseProgram(program->service_id());
      if (workarounds().clear_uniforms_before_first_program_use)
        program_manager()->ClearUniforms(program);
    }
  }
};

void GLES2DecoderImpl::DoTexParameterf(
    GLenum target, GLenum pname, GLfloat param) {
  TextureRef* texture = texture_manager()->GetTextureInfoForTarget(
      &state_, target);
  if (!texture) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "glTexParameterf", "unknown texture");
    return;
  }

  texture_manager()->SetParameterf(
      "glTexParameterf", GetErrorState(), texture, pname, param);
}

void GLES2DecoderImpl::DoTexParameteri(
    GLenum target, GLenum pname, GLint param) {
  TextureRef* texture = texture_manager()->GetTextureInfoForTarget(
      &state_, target);
  if (!texture) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "glTexParameteri", "unknown texture");
    return;
  }

  texture_manager()->SetParameteri(
      "glTexParameteri", GetErrorState(), texture, pname, param);
}

void GLES2DecoderImpl::DoTexParameterfv(
    GLenum target, GLenum pname, const GLfloat* params) {
  TextureRef* texture = texture_manager()->GetTextureInfoForTarget(
      &state_, target);
  if (!texture) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "glTexParameterfv", "unknown texture");
    return;
  }

  texture_manager()->SetParameterf(
      "glTexParameterfv", GetErrorState(), texture, pname, *params);
}

void GLES2DecoderImpl::DoTexParameteriv(
  GLenum target, GLenum pname, const GLint* params) {
  TextureRef* texture = texture_manager()->GetTextureInfoForTarget(
      &state_, target);
  if (!texture) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glTexParameteriv", "unknown texture");
    return;
  }

  texture_manager()->SetParameteri(
      "glTexParameteriv", GetErrorState(), texture, pname, *params);
}

bool GLES2DecoderImpl::CheckCurrentProgram(const char* function_name) {
  if (!state_.current_program.get()) {
    // The program does not exist.
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, function_name, "no program in use");
    return false;
  }
  if (!state_.current_program->InUse()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, function_name, "program not linked");
    return false;
  }
  return true;
}

bool GLES2DecoderImpl::CheckCurrentProgramForUniform(
    GLint location, const char* function_name) {
  if (!CheckCurrentProgram(function_name)) {
    return false;
  }
  return location != -1;
}

bool GLES2DecoderImpl::PrepForSetUniformByLocation(
    GLint fake_location,
    const char* function_name,
    Program::UniformApiType api_type,
    GLint* real_location,
    GLenum* type,
    GLsizei* count) {
  DCHECK(type);
  DCHECK(count);
  DCHECK(real_location);

  if (!CheckCurrentProgramForUniform(fake_location, function_name)) {
    return false;
  }
  GLint array_index = -1;
  const Program::UniformInfo* info =
      state_.current_program->GetUniformInfoByFakeLocation(
          fake_location, real_location, &array_index);
  if (!info) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, function_name, "unknown location");
    return false;
  }

  if ((api_type & info->accepts_api_type) == 0) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, function_name,
        "wrong uniform function for type");
    return false;
  }
  if (*count > 1 && !info->is_array) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, function_name, "count > 1 for non-array");
    return false;
  }
  *count = std::min(info->size - array_index, *count);
  if (*count <= 0) {
    return false;
  }
  *type = info->type;
  return true;
}

void GLES2DecoderImpl::DoUniform1i(GLint fake_location, GLint v0) {
  GLenum type = 0;
  GLsizei count = 1;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniform1i",
                                   Program::kUniform1i,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  if (!state_.current_program->SetSamplers(
      state_.texture_units.size(), fake_location, 1, &v0)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glUniform1i", "texture unit out of range");
    return;
  }
  glUniform1i(real_location, v0);
}

void GLES2DecoderImpl::DoUniform1iv(
    GLint fake_location, GLsizei count, const GLint *value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniform1iv",
                                   Program::kUniform1i,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  if (type == GL_SAMPLER_2D || type == GL_SAMPLER_2D_RECT_ARB ||
      type == GL_SAMPLER_CUBE || type == GL_SAMPLER_EXTERNAL_OES) {
    if (!state_.current_program->SetSamplers(
          state_.texture_units.size(), fake_location, count, value)) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_VALUE, "glUniform1iv", "texture unit out of range");
      return;
    }
  }
  glUniform1iv(real_location, count, value);
}

void GLES2DecoderImpl::DoUniform1fv(
    GLint fake_location, GLsizei count, const GLfloat* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniform1fv",
                                   Program::kUniform1f,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  if (type == GL_BOOL) {
    scoped_ptr<GLint[]> temp(new GLint[count]);
    for (GLsizei ii = 0; ii < count; ++ii) {
      temp[ii] = static_cast<GLint>(value[ii] != 0.0f);
    }
    DoUniform1iv(real_location, count, temp.get());
  } else {
    glUniform1fv(real_location, count, value);
  }
}

void GLES2DecoderImpl::DoUniform2fv(
    GLint fake_location, GLsizei count, const GLfloat* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniform2fv",
                                   Program::kUniform2f,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  if (type == GL_BOOL_VEC2) {
    GLsizei num_values = count * 2;
    scoped_ptr<GLint[]> temp(new GLint[num_values]);
    for (GLsizei ii = 0; ii < num_values; ++ii) {
      temp[ii] = static_cast<GLint>(value[ii] != 0.0f);
    }
    glUniform2iv(real_location, count, temp.get());
  } else {
    glUniform2fv(real_location, count, value);
  }
}

void GLES2DecoderImpl::DoUniform3fv(
    GLint fake_location, GLsizei count, const GLfloat* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniform3fv",
                                   Program::kUniform3f,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  if (type == GL_BOOL_VEC3) {
    GLsizei num_values = count * 3;
    scoped_ptr<GLint[]> temp(new GLint[num_values]);
    for (GLsizei ii = 0; ii < num_values; ++ii) {
      temp[ii] = static_cast<GLint>(value[ii] != 0.0f);
    }
    glUniform3iv(real_location, count, temp.get());
  } else {
    glUniform3fv(real_location, count, value);
  }
}

void GLES2DecoderImpl::DoUniform4fv(
    GLint fake_location, GLsizei count, const GLfloat* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniform4fv",
                                   Program::kUniform4f,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  if (type == GL_BOOL_VEC4) {
    GLsizei num_values = count * 4;
    scoped_ptr<GLint[]> temp(new GLint[num_values]);
    for (GLsizei ii = 0; ii < num_values; ++ii) {
      temp[ii] = static_cast<GLint>(value[ii] != 0.0f);
    }
    glUniform4iv(real_location, count, temp.get());
  } else {
    glUniform4fv(real_location, count, value);
  }
}

void GLES2DecoderImpl::DoUniform2iv(
    GLint fake_location, GLsizei count, const GLint* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniform2iv",
                                   Program::kUniform2i,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  glUniform2iv(real_location, count, value);
}

void GLES2DecoderImpl::DoUniform3iv(
    GLint fake_location, GLsizei count, const GLint* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniform3iv",
                                   Program::kUniform3i,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  glUniform3iv(real_location, count, value);
}

void GLES2DecoderImpl::DoUniform4iv(
    GLint fake_location, GLsizei count, const GLint* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniform4iv",
                                   Program::kUniform4i,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  glUniform4iv(real_location, count, value);
}

void GLES2DecoderImpl::DoUniformMatrix2fv(
    GLint fake_location, GLsizei count, GLboolean transpose,
    const GLfloat* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniformMatrix2fv",
                                   Program::kUniformMatrix2f,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  glUniformMatrix2fv(real_location, count, transpose, value);
}

void GLES2DecoderImpl::DoUniformMatrix3fv(
    GLint fake_location, GLsizei count, GLboolean transpose,
    const GLfloat* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniformMatrix3fv",
                                   Program::kUniformMatrix3f,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  glUniformMatrix3fv(real_location, count, transpose, value);
}

void GLES2DecoderImpl::DoUniformMatrix4fv(
    GLint fake_location, GLsizei count, GLboolean transpose,
    const GLfloat* value) {
  GLenum type = 0;
  GLint real_location = -1;
  if (!PrepForSetUniformByLocation(fake_location,
                                   "glUniformMatrix4fv",
                                   Program::kUniformMatrix4f,
                                   &real_location,
                                   &type,
                                   &count)) {
    return;
  }
  glUniformMatrix4fv(real_location, count, transpose, value);
}

void GLES2DecoderImpl::DoUseProgram(GLuint program_id) {
  GLuint service_id = 0;
  Program* program = NULL;
  if (program_id) {
    program = GetProgramInfoNotShader(program_id, "glUseProgram");
    if (!program) {
      return;
    }
    if (!program->IsValid()) {
      // Program was not linked successfully. (ie, glLinkProgram)
      LOCAL_SET_GL_ERROR(
          GL_INVALID_OPERATION, "glUseProgram", "program not linked");
      return;
    }
    service_id = program->service_id();
  }
  if (state_.current_program.get()) {
    program_manager()->UnuseProgram(shader_manager(),
                                    state_.current_program.get());
  }
  state_.current_program = program;
  LogClientServiceMapping("glUseProgram", program_id, service_id);
  glUseProgram(service_id);
  if (state_.current_program.get()) {
    program_manager()->UseProgram(state_.current_program.get());
    if (workarounds().clear_uniforms_before_first_program_use)
      program_manager()->ClearUniforms(program);
  }
}

void GLES2DecoderImpl::RenderWarning(
    const char* filename, int line, const std::string& msg) {
  logger_.LogMessage(filename, line, std::string("RENDER WARNING: ") + msg);
}

void GLES2DecoderImpl::PerformanceWarning(
    const char* filename, int line, const std::string& msg) {
  logger_.LogMessage(filename, line,
                     std::string("PERFORMANCE WARNING: ") + msg);
}

void GLES2DecoderImpl::DoWillUseTexImageIfNeeded(
    Texture* texture, GLenum textarget) {
  // Image is already in use if texture is attached to a framebuffer.
  if (texture && !texture->IsAttachedToFramebuffer()) {
    gfx::GLImage* image = texture->GetLevelImage(textarget, 0);
    if (image) {
      ScopedGLErrorSuppressor suppressor(
          "GLES2DecoderImpl::DoWillUseTexImageIfNeeded",
          GetErrorState());
      glBindTexture(textarget, texture->service_id());
      image->WillUseTexImage();
      RestoreCurrentTextureBindings(&state_, textarget);
    }
  }
}

void GLES2DecoderImpl::DoDidUseTexImageIfNeeded(
    Texture* texture, GLenum textarget) {
  // Image is still in use if texture is attached to a framebuffer.
  if (texture && !texture->IsAttachedToFramebuffer()) {
    gfx::GLImage* image = texture->GetLevelImage(textarget, 0);
    if (image) {
      ScopedGLErrorSuppressor suppressor(
          "GLES2DecoderImpl::DoDidUseTexImageIfNeeded",
          GetErrorState());
      glBindTexture(textarget, texture->service_id());
      image->DidUseTexImage();
      RestoreCurrentTextureBindings(&state_, textarget);
    }
  }
}

bool GLES2DecoderImpl::PrepareTexturesForRender() {
  DCHECK(state_.current_program.get());
  if (!texture_manager()->HaveUnrenderableTextures() &&
      !texture_manager()->HaveImages()) {
    return true;
  }

  bool textures_set = false;
  const Program::SamplerIndices& sampler_indices =
     state_.current_program->sampler_indices();
  for (size_t ii = 0; ii < sampler_indices.size(); ++ii) {
    const Program::UniformInfo* uniform_info =
        state_.current_program->GetUniformInfo(sampler_indices[ii]);
    DCHECK(uniform_info);
    for (size_t jj = 0; jj < uniform_info->texture_units.size(); ++jj) {
      GLuint texture_unit_index = uniform_info->texture_units[jj];
      if (texture_unit_index < state_.texture_units.size()) {
        TextureUnit& texture_unit = state_.texture_units[texture_unit_index];
        TextureRef* texture_ref =
            texture_unit.GetInfoForSamplerType(uniform_info->type).get();
        GLenum textarget = GetBindTargetForSamplerType(uniform_info->type);
        if (!texture_ref || !texture_manager()->CanRender(texture_ref)) {
          textures_set = true;
          glActiveTexture(GL_TEXTURE0 + texture_unit_index);
          glBindTexture(
              textarget,
              texture_manager()->black_texture_id(uniform_info->type));
          LOCAL_RENDER_WARNING(
              std::string("texture bound to texture unit ") +
              base::IntToString(texture_unit_index) +
              " is not renderable. It maybe non-power-of-2 and have"
              " incompatible texture filtering or is not"
              " 'texture complete'");
          continue;
        }

        if (textarget != GL_TEXTURE_CUBE_MAP) {
          Texture* texture = texture_ref->texture();
          gfx::GLImage* image = texture->GetLevelImage(textarget, 0);
          if (image && !texture->IsAttachedToFramebuffer()) {
            ScopedGLErrorSuppressor suppressor(
                "GLES2DecoderImpl::PrepareTexturesForRender", GetErrorState());
            textures_set = true;
            glActiveTexture(GL_TEXTURE0 + texture_unit_index);
            image->WillUseTexImage();
            continue;
          }
        }
      }
      // else: should this be an error?
    }
  }
  return !textures_set;
}

void GLES2DecoderImpl::RestoreStateForTextures() {
  DCHECK(state_.current_program.get());
  const Program::SamplerIndices& sampler_indices =
      state_.current_program->sampler_indices();
  for (size_t ii = 0; ii < sampler_indices.size(); ++ii) {
    const Program::UniformInfo* uniform_info =
        state_.current_program->GetUniformInfo(sampler_indices[ii]);
    DCHECK(uniform_info);
    for (size_t jj = 0; jj < uniform_info->texture_units.size(); ++jj) {
      GLuint texture_unit_index = uniform_info->texture_units[jj];
      if (texture_unit_index < state_.texture_units.size()) {
        TextureUnit& texture_unit = state_.texture_units[texture_unit_index];
        TextureRef* texture_ref =
            texture_unit.GetInfoForSamplerType(uniform_info->type).get();
        if (!texture_ref || !texture_manager()->CanRender(texture_ref)) {
          glActiveTexture(GL_TEXTURE0 + texture_unit_index);
          // Get the texture_ref info that was previously bound here.
          texture_ref = texture_unit.bind_target == GL_TEXTURE_2D
                            ? texture_unit.bound_texture_2d.get()
                            : texture_unit.bound_texture_cube_map.get();
          glBindTexture(texture_unit.bind_target,
                        texture_ref ? texture_ref->service_id() : 0);
          continue;
        }

        if (texture_unit.bind_target != GL_TEXTURE_CUBE_MAP) {
          Texture* texture = texture_ref->texture();
          gfx::GLImage* image =
              texture->GetLevelImage(texture_unit.bind_target, 0);
          if (image && !texture->IsAttachedToFramebuffer()) {
            ScopedGLErrorSuppressor suppressor(
                "GLES2DecoderImpl::RestoreStateForTextures", GetErrorState());
            glActiveTexture(GL_TEXTURE0 + texture_unit_index);
            image->DidUseTexImage();
            continue;
          }
        }
      }
    }
  }
  // Set the active texture back to whatever the user had it as.
  glActiveTexture(GL_TEXTURE0 + state_.active_texture_unit);
}

bool GLES2DecoderImpl::ClearUnclearedTextures() {
  // Only check if there are some uncleared textures.
  if (!texture_manager()->HaveUnsafeTextures()) {
    return true;
  }

  // 1: Check all textures we are about to render with.
  if (state_.current_program.get()) {
    const Program::SamplerIndices& sampler_indices =
        state_.current_program->sampler_indices();
    for (size_t ii = 0; ii < sampler_indices.size(); ++ii) {
      const Program::UniformInfo* uniform_info =
          state_.current_program->GetUniformInfo(sampler_indices[ii]);
      DCHECK(uniform_info);
      for (size_t jj = 0; jj < uniform_info->texture_units.size(); ++jj) {
        GLuint texture_unit_index = uniform_info->texture_units[jj];
        if (texture_unit_index < state_.texture_units.size()) {
          TextureUnit& texture_unit = state_.texture_units[texture_unit_index];
          TextureRef* texture_ref =
              texture_unit.GetInfoForSamplerType(uniform_info->type).get();
          if (texture_ref && !texture_ref->texture()->SafeToRenderFrom()) {
            if (!texture_manager()->ClearRenderableLevels(this, texture_ref)) {
              return false;
            }
          }
        }
      }
    }
  }
  return true;
}

bool GLES2DecoderImpl::IsDrawValid(
    const char* function_name, GLuint max_vertex_accessed, GLsizei primcount) {
  // NOTE: We specifically do not check current_program->IsValid() because
  // it could never be invalid since glUseProgram would have failed. While
  // glLinkProgram could later mark the program as invalid the previous
  // valid program will still function if it is still the current program.
  if (!state_.current_program.get()) {
    // The program does not exist.
    // But GL says no ERROR.
    LOCAL_RENDER_WARNING("Drawing with no current shader program.");
    return false;
  }

  return state_.vertex_attrib_manager
      ->ValidateBindings(function_name,
                         this,
                         feature_info_.get(),
                         state_.current_program.get(),
                         max_vertex_accessed,
                         primcount);
}

bool GLES2DecoderImpl::SimulateAttrib0(
    const char* function_name, GLuint max_vertex_accessed, bool* simulated) {
  DCHECK(simulated);
  *simulated = false;

  if (gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2)
    return true;

  const VertexAttrib* attrib =
      state_.vertex_attrib_manager->GetVertexAttrib(0);
  // If it's enabled or it's not used then we don't need to do anything.
  bool attrib_0_used =
      state_.current_program->GetAttribInfoByLocation(0) != NULL;
  if (attrib->enabled() && attrib_0_used) {
    return true;
  }

  // Make a buffer with a single repeated vec4 value enough to
  // simulate the constant value that is supposed to be here.
  // This is required to emulate GLES2 on GL.
  GLuint num_vertices = max_vertex_accessed + 1;
  uint32 size_needed = 0;

  if (num_vertices == 0 ||
      !SafeMultiplyUint32(num_vertices, sizeof(Vec4), &size_needed) ||
      size_needed > 0x7FFFFFFFU) {
    LOCAL_SET_GL_ERROR(GL_OUT_OF_MEMORY, function_name, "Simulating attrib 0");
    return false;
  }

  LOCAL_PERFORMANCE_WARNING(
      "Attribute 0 is disabled. This has signficant performance penalty");

  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER(function_name);
  glBindBuffer(GL_ARRAY_BUFFER, attrib_0_buffer_id_);

  bool new_buffer = static_cast<GLsizei>(size_needed) > attrib_0_size_;
  if (new_buffer) {
    glBufferData(GL_ARRAY_BUFFER, size_needed, NULL, GL_DYNAMIC_DRAW);
    GLenum error = glGetError();
    if (error != GL_NO_ERROR) {
      LOCAL_SET_GL_ERROR(
          GL_OUT_OF_MEMORY, function_name, "Simulating attrib 0");
      return false;
    }
  }

  const Vec4& value = state_.attrib_values[0];
  if (new_buffer ||
      (attrib_0_used &&
       (!attrib_0_buffer_matches_value_ ||
        (value.v[0] != attrib_0_value_.v[0] ||
         value.v[1] != attrib_0_value_.v[1] ||
         value.v[2] != attrib_0_value_.v[2] ||
         value.v[3] != attrib_0_value_.v[3])))) {
    std::vector<Vec4> temp(num_vertices, value);
    glBufferSubData(GL_ARRAY_BUFFER, 0, size_needed, &temp[0].v[0]);
    attrib_0_buffer_matches_value_ = true;
    attrib_0_value_ = value;
    attrib_0_size_ = size_needed;
  }

  glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, NULL);

  if (attrib->divisor())
    glVertexAttribDivisorANGLE(0, 0);

  *simulated = true;
  return true;
}

void GLES2DecoderImpl::RestoreStateForAttrib(
    GLuint attrib_index, bool restore_array_binding) {
  const VertexAttrib* attrib =
      state_.vertex_attrib_manager->GetVertexAttrib(attrib_index);
  if (restore_array_binding) {
    const void* ptr = reinterpret_cast<const void*>(attrib->offset());
    Buffer* buffer = attrib->buffer();
    glBindBuffer(GL_ARRAY_BUFFER, buffer ? buffer->service_id() : 0);
    glVertexAttribPointer(
        attrib_index, attrib->size(), attrib->type(), attrib->normalized(),
        attrib->gl_stride(), ptr);
  }
  if (attrib->divisor())
    glVertexAttribDivisorANGLE(attrib_index, attrib->divisor());
  glBindBuffer(
      GL_ARRAY_BUFFER, state_.bound_array_buffer.get() ?
          state_.bound_array_buffer->service_id() : 0);

  // Never touch vertex attribute 0's state (in particular, never
  // disable it) when running on desktop GL because it will never be
  // re-enabled.
  if (attrib_index != 0 ||
      gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2) {
    if (attrib->enabled()) {
      glEnableVertexAttribArray(attrib_index);
    } else {
      glDisableVertexAttribArray(attrib_index);
    }
  }
}

bool GLES2DecoderImpl::SimulateFixedAttribs(
    const char* function_name,
    GLuint max_vertex_accessed, bool* simulated, GLsizei primcount) {
  DCHECK(simulated);
  *simulated = false;
  if (gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2)
    return true;

  if (!state_.vertex_attrib_manager->HaveFixedAttribs()) {
    return true;
  }

  LOCAL_PERFORMANCE_WARNING(
      "GL_FIXED attributes have a signficant performance penalty");

  // NOTE: we could be smart and try to check if a buffer is used
  // twice in 2 different attribs, find the overlapping parts and therefore
  // duplicate the minimum amount of data but this whole code path is not meant
  // to be used normally. It's just here to pass that OpenGL ES 2.0 conformance
  // tests so we just add to the buffer attrib used.

  GLuint elements_needed = 0;
  const VertexAttribManager::VertexAttribList& enabled_attribs =
      state_.vertex_attrib_manager->GetEnabledVertexAttribs();
  for (VertexAttribManager::VertexAttribList::const_iterator it =
       enabled_attribs.begin(); it != enabled_attribs.end(); ++it) {
    const VertexAttrib* attrib = *it;
    const Program::VertexAttrib* attrib_info =
        state_.current_program->GetAttribInfoByLocation(attrib->index());
    GLuint max_accessed = attrib->MaxVertexAccessed(primcount,
                                                    max_vertex_accessed);
    GLuint num_vertices = max_accessed + 1;
    if (num_vertices == 0) {
      LOCAL_SET_GL_ERROR(
          GL_OUT_OF_MEMORY, function_name, "Simulating attrib 0");
      return false;
    }
    if (attrib_info &&
        attrib->CanAccess(max_accessed) &&
        attrib->type() == GL_FIXED) {
      uint32 elements_used = 0;
      if (!SafeMultiplyUint32(num_vertices, attrib->size(), &elements_used) ||
          !SafeAddUint32(elements_needed, elements_used, &elements_needed)) {
        LOCAL_SET_GL_ERROR(
            GL_OUT_OF_MEMORY, function_name, "simulating GL_FIXED attribs");
        return false;
      }
    }
  }

  const uint32 kSizeOfFloat = sizeof(float);  // NOLINT
  uint32 size_needed = 0;
  if (!SafeMultiplyUint32(elements_needed, kSizeOfFloat, &size_needed) ||
      size_needed > 0x7FFFFFFFU) {
    LOCAL_SET_GL_ERROR(
        GL_OUT_OF_MEMORY, function_name, "simulating GL_FIXED attribs");
    return false;
  }

  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER(function_name);

  glBindBuffer(GL_ARRAY_BUFFER, fixed_attrib_buffer_id_);
  if (static_cast<GLsizei>(size_needed) > fixed_attrib_buffer_size_) {
    glBufferData(GL_ARRAY_BUFFER, size_needed, NULL, GL_DYNAMIC_DRAW);
    GLenum error = glGetError();
    if (error != GL_NO_ERROR) {
      LOCAL_SET_GL_ERROR(
          GL_OUT_OF_MEMORY, function_name, "simulating GL_FIXED attribs");
      return false;
    }
  }

  // Copy the elements and convert to float
  GLintptr offset = 0;
  for (VertexAttribManager::VertexAttribList::const_iterator it =
       enabled_attribs.begin(); it != enabled_attribs.end(); ++it) {
    const VertexAttrib* attrib = *it;
    const Program::VertexAttrib* attrib_info =
        state_.current_program->GetAttribInfoByLocation(attrib->index());
    GLuint max_accessed = attrib->MaxVertexAccessed(primcount,
                                                  max_vertex_accessed);
    GLuint num_vertices = max_accessed + 1;
    if (num_vertices == 0) {
      LOCAL_SET_GL_ERROR(
          GL_OUT_OF_MEMORY, function_name, "Simulating attrib 0");
      return false;
    }
    if (attrib_info &&
        attrib->CanAccess(max_accessed) &&
        attrib->type() == GL_FIXED) {
      int num_elements = attrib->size() * kSizeOfFloat;
      int size = num_elements * num_vertices;
      scoped_ptr<float[]> data(new float[size]);
      const int32* src = reinterpret_cast<const int32 *>(
          attrib->buffer()->GetRange(attrib->offset(), size));
      const int32* end = src + num_elements;
      float* dst = data.get();
      while (src != end) {
        *dst++ = static_cast<float>(*src++) / 65536.0f;
      }
      glBufferSubData(GL_ARRAY_BUFFER, offset, size, data.get());
      glVertexAttribPointer(
          attrib->index(), attrib->size(), GL_FLOAT, false, 0,
          reinterpret_cast<GLvoid*>(offset));
      offset += size;
    }
  }
  *simulated = true;
  return true;
}

void GLES2DecoderImpl::RestoreStateForSimulatedFixedAttribs() {
  // There's no need to call glVertexAttribPointer because we shadow all the
  // settings and passing GL_FIXED to it will not work.
  glBindBuffer(
      GL_ARRAY_BUFFER,
      state_.bound_array_buffer.get() ? state_.bound_array_buffer->service_id()
                                      : 0);
}

error::Error GLES2DecoderImpl::DoDrawArrays(
    const char* function_name,
    bool instanced,
    GLenum mode,
    GLint first,
    GLsizei count,
    GLsizei primcount) {
  error::Error error = WillAccessBoundFramebufferForDraw();
  if (error != error::kNoError)
    return error;
  if (!validators_->draw_mode.IsValid(mode)) {
    LOCAL_SET_GL_ERROR_INVALID_ENUM(function_name, mode, "mode");
    return error::kNoError;
  }
  if (count < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "count < 0");
    return error::kNoError;
  }
  if (primcount < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "primcount < 0");
    return error::kNoError;
  }
  if (!CheckBoundFramebuffersValid(function_name)) {
    return error::kNoError;
  }
  // We have to check this here because the prototype for glDrawArrays
  // is GLint not GLsizei.
  if (first < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "first < 0");
    return error::kNoError;
  }

  if (count == 0 || (instanced && primcount == 0)) {
    LOCAL_RENDER_WARNING("Render count or primcount is 0.");
    return error::kNoError;
  }

  GLuint max_vertex_accessed = first + count - 1;
  if (IsDrawValid(function_name, max_vertex_accessed, primcount)) {
    if (!ClearUnclearedTextures()) {
      LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "out of memory");
      return error::kNoError;
    }
    bool simulated_attrib_0 = false;
    if (!SimulateAttrib0(
        function_name, max_vertex_accessed, &simulated_attrib_0)) {
      return error::kNoError;
    }
    bool simulated_fixed_attribs = false;
    if (SimulateFixedAttribs(
        function_name, max_vertex_accessed, &simulated_fixed_attribs,
        primcount)) {
      bool textures_set = !PrepareTexturesForRender();
      ApplyDirtyState();
      ScopedRenderTo do_render(framebuffer_state_.bound_draw_framebuffer.get());
      if (!instanced) {
        glDrawArrays(mode, first, count);
      } else {
        glDrawArraysInstancedANGLE(mode, first, count, primcount);
      }
      if (textures_set) {
        RestoreStateForTextures();
      }
      if (simulated_fixed_attribs) {
        RestoreStateForSimulatedFixedAttribs();
      }
    }
    if (simulated_attrib_0) {
      // We don't have to restore attrib 0 generic data at the end of this
      // function even if it is simulated. This is because we will simulate
      // it in each draw call, and attrib 0 generic data queries use cached
      // values instead of passing down to the underlying driver.
      RestoreStateForAttrib(0, false);
    }
  }
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleDrawArrays(
    uint32 immediate_data_size, const cmds::DrawArrays& c) {
  return DoDrawArrays("glDrawArrays",
                      false,
                      static_cast<GLenum>(c.mode),
                      static_cast<GLint>(c.first),
                      static_cast<GLsizei>(c.count),
                      0);
}

error::Error GLES2DecoderImpl::HandleDrawArraysInstancedANGLE(
    uint32 immediate_data_size, const cmds::DrawArraysInstancedANGLE& c) {
  if (!features().angle_instanced_arrays) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glDrawArraysInstancedANGLE", "function not available");
    return error::kNoError;
  }
  return DoDrawArrays("glDrawArraysIntancedANGLE",
                      true,
                      static_cast<GLenum>(c.mode),
                      static_cast<GLint>(c.first),
                      static_cast<GLsizei>(c.count),
                      static_cast<GLsizei>(c.primcount));
}

error::Error GLES2DecoderImpl::DoDrawElements(
    const char* function_name,
    bool instanced,
    GLenum mode,
    GLsizei count,
    GLenum type,
    int32 offset,
    GLsizei primcount) {
  error::Error error = WillAccessBoundFramebufferForDraw();
  if (error != error::kNoError)
    return error;
  if (!state_.vertex_attrib_manager->element_array_buffer()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, function_name, "No element array buffer bound");
    return error::kNoError;
  }

  if (count < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "count < 0");
    return error::kNoError;
  }
  if (offset < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "offset < 0");
    return error::kNoError;
  }
  if (!validators_->draw_mode.IsValid(mode)) {
    LOCAL_SET_GL_ERROR_INVALID_ENUM(function_name, mode, "mode");
    return error::kNoError;
  }
  if (!validators_->index_type.IsValid(type)) {
    LOCAL_SET_GL_ERROR_INVALID_ENUM(function_name, type, "type");
    return error::kNoError;
  }
  if (primcount < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "primcount < 0");
    return error::kNoError;
  }

  if (!CheckBoundFramebuffersValid(function_name)) {
    return error::kNoError;
  }

  if (count == 0 || (instanced && primcount == 0)) {
    return error::kNoError;
  }

  GLuint max_vertex_accessed;
  Buffer* element_array_buffer =
      state_.vertex_attrib_manager->element_array_buffer();

  if (!element_array_buffer->GetMaxValueForRange(
      offset, count, type, &max_vertex_accessed)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, function_name, "range out of bounds for buffer");
    return error::kNoError;
  }

  if (IsDrawValid(function_name, max_vertex_accessed, primcount)) {
    if (!ClearUnclearedTextures()) {
      LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "out of memory");
      return error::kNoError;
    }
    bool simulated_attrib_0 = false;
    if (!SimulateAttrib0(
        function_name, max_vertex_accessed, &simulated_attrib_0)) {
      return error::kNoError;
    }
    bool simulated_fixed_attribs = false;
    if (SimulateFixedAttribs(
        function_name, max_vertex_accessed, &simulated_fixed_attribs,
        primcount)) {
      bool textures_set = !PrepareTexturesForRender();
      ApplyDirtyState();
      // TODO(gman): Refactor to hide these details in BufferManager or
      // VertexAttribManager.
      const GLvoid* indices = reinterpret_cast<const GLvoid*>(offset);
      bool used_client_side_array = false;
      if (element_array_buffer->IsClientSideArray()) {
        used_client_side_array = true;
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
        indices = element_array_buffer->GetRange(offset, 0);
      }

      ScopedRenderTo do_render(framebuffer_state_.bound_draw_framebuffer.get());
      if (!instanced) {
        glDrawElements(mode, count, type, indices);
      } else {
        glDrawElementsInstancedANGLE(mode, count, type, indices, primcount);
      }

      if (used_client_side_array) {
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,
                     element_array_buffer->service_id());
      }

      if (textures_set) {
        RestoreStateForTextures();
      }
      if (simulated_fixed_attribs) {
        RestoreStateForSimulatedFixedAttribs();
      }
    }
    if (simulated_attrib_0) {
      // We don't have to restore attrib 0 generic data at the end of this
      // function even if it is simulated. This is because we will simulate
      // it in each draw call, and attrib 0 generic data queries use cached
      // values instead of passing down to the underlying driver.
      RestoreStateForAttrib(0, false);
    }
  }
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleDrawElements(
    uint32 immediate_data_size, const cmds::DrawElements& c) {
  return DoDrawElements("glDrawElements",
                        false,
                        static_cast<GLenum>(c.mode),
                        static_cast<GLsizei>(c.count),
                        static_cast<GLenum>(c.type),
                        static_cast<int32>(c.index_offset),
                        0);
}

error::Error GLES2DecoderImpl::HandleDrawElementsInstancedANGLE(
    uint32 immediate_data_size, const cmds::DrawElementsInstancedANGLE& c) {
  if (!features().angle_instanced_arrays) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glDrawElementsInstancedANGLE", "function not available");
    return error::kNoError;
  }
  return DoDrawElements("glDrawElementsInstancedANGLE",
                        true,
                        static_cast<GLenum>(c.mode),
                        static_cast<GLsizei>(c.count),
                        static_cast<GLenum>(c.type),
                        static_cast<int32>(c.index_offset),
                        static_cast<GLsizei>(c.primcount));
}

GLuint GLES2DecoderImpl::DoGetMaxValueInBufferCHROMIUM(
    GLuint buffer_id, GLsizei count, GLenum type, GLuint offset) {
  GLuint max_vertex_accessed = 0;
  Buffer* buffer = GetBuffer(buffer_id);
  if (!buffer) {
    // TODO(gman): Should this be a GL error or a command buffer error?
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "GetMaxValueInBufferCHROMIUM", "unknown buffer");
  } else {
    if (!buffer->GetMaxValueForRange(
        offset, count, type, &max_vertex_accessed)) {
      // TODO(gman): Should this be a GL error or a command buffer error?
      LOCAL_SET_GL_ERROR(
          GL_INVALID_OPERATION,
          "GetMaxValueInBufferCHROMIUM", "range out of bounds for buffer");
    }
  }
  return max_vertex_accessed;
}

// Calls glShaderSource for the various versions of the ShaderSource command.
// Assumes that data / data_size points to a piece of memory that is in range
// of whatever context it came from (shared memory, immediate memory, bucket
// memory.)
error::Error GLES2DecoderImpl::ShaderSourceHelper(
    GLuint client_id, const char* data, uint32 data_size) {
  std::string str(data, data + data_size);
  Shader* shader = GetShaderInfoNotProgram(client_id, "glShaderSource");
  if (!shader) {
    return error::kNoError;
  }
  // Note: We don't actually call glShaderSource here. We wait until
  // the call to glCompileShader.
  shader->UpdateSource(str.c_str());
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleShaderSourceBucket(
  uint32 immediate_data_size, const cmds::ShaderSourceBucket& c) {
  Bucket* bucket = GetBucket(c.data_bucket_id);
  if (!bucket || bucket->size() == 0) {
    return error::kInvalidArguments;
  }
  return ShaderSourceHelper(
      c.shader, bucket->GetDataAs<const char*>(0, bucket->size() - 1),
      bucket->size() - 1);
}

void GLES2DecoderImpl::DoCompileShader(GLuint client_id) {
  TRACE_EVENT0("gpu", "GLES2DecoderImpl::DoCompileShader");
  Shader* shader = GetShaderInfoNotProgram(client_id, "glCompileShader");
  if (!shader) {
    return;
  }
  ShaderTranslator* translator = NULL;
  if (use_shader_translator_) {
    translator = shader->shader_type() == GL_VERTEX_SHADER ?
        vertex_translator_.get() : fragment_translator_.get();
  }

  program_manager()->DoCompileShader(
     shader,
     translator,
     feature_info_->feature_flags().angle_translated_shader_source ?
         ProgramManager::kANGLE : ProgramManager::kGL);
};

void GLES2DecoderImpl::DoGetShaderiv(
    GLuint shader_id, GLenum pname, GLint* params) {
  Shader* shader = GetShaderInfoNotProgram(shader_id, "glGetShaderiv");
  if (!shader) {
    return;
  }
  switch (pname) {
    case GL_SHADER_SOURCE_LENGTH:
      *params = shader->source() ? shader->source()->size() + 1 : 0;
      return;
    case GL_COMPILE_STATUS:
      *params = compile_shader_always_succeeds_ ? true : shader->IsValid();
      return;
    case GL_INFO_LOG_LENGTH:
      *params = shader->log_info() ? shader->log_info()->size() + 1 : 0;
      return;
    case GL_TRANSLATED_SHADER_SOURCE_LENGTH_ANGLE:
      *params = shader->translated_source() ?
          shader->translated_source()->size() + 1 : 0;
      return;
    default:
      break;
  }
  glGetShaderiv(shader->service_id(), pname, params);
}

error::Error GLES2DecoderImpl::HandleGetShaderSource(
    uint32 immediate_data_size, const cmds::GetShaderSource& c) {
  GLuint shader_id = c.shader;
  uint32 bucket_id = static_cast<uint32>(c.bucket_id);
  Bucket* bucket = CreateBucket(bucket_id);
  Shader* shader = GetShaderInfoNotProgram(shader_id, "glGetShaderSource");
  if (!shader || !shader->source()) {
    bucket->SetSize(0);
    return error::kNoError;
  }
  bucket->SetFromString(shader->source()->c_str());
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleGetTranslatedShaderSourceANGLE(
    uint32 immediate_data_size,
    const cmds::GetTranslatedShaderSourceANGLE& c) {
  GLuint shader_id = c.shader;
  uint32 bucket_id = static_cast<uint32>(c.bucket_id);
  Bucket* bucket = CreateBucket(bucket_id);
  Shader* shader = GetShaderInfoNotProgram(
      shader_id, "glGetTranslatedShaderSourceANGLE");
  if (!shader) {
    bucket->SetSize(0);
    return error::kNoError;
  }

  bucket->SetFromString(shader->translated_source() ?
      shader->translated_source()->c_str() : NULL);
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleGetProgramInfoLog(
    uint32 immediate_data_size, const cmds::GetProgramInfoLog& c) {
  GLuint program_id = c.program;
  uint32 bucket_id = static_cast<uint32>(c.bucket_id);
  Bucket* bucket = CreateBucket(bucket_id);
  Program* program = GetProgramInfoNotShader(
      program_id, "glGetProgramInfoLog");
  if (!program || !program->log_info()) {
    bucket->SetFromString("");
    return error::kNoError;
  }
  bucket->SetFromString(program->log_info()->c_str());
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleGetShaderInfoLog(
    uint32 immediate_data_size, const cmds::GetShaderInfoLog& c) {
  GLuint shader_id = c.shader;
  uint32 bucket_id = static_cast<uint32>(c.bucket_id);
  Bucket* bucket = CreateBucket(bucket_id);
  Shader* shader = GetShaderInfoNotProgram(shader_id, "glGetShaderInfoLog");
  if (!shader || !shader->log_info()) {
    bucket->SetFromString("");
    return error::kNoError;
  }
  bucket->SetFromString(shader->log_info()->c_str());
  return error::kNoError;
}

bool GLES2DecoderImpl::DoIsEnabled(GLenum cap) {
  return state_.GetEnabled(cap);
}

bool GLES2DecoderImpl::DoIsBuffer(GLuint client_id) {
  const Buffer* buffer = GetBuffer(client_id);
  return buffer && buffer->IsValid() && !buffer->IsDeleted();
}

bool GLES2DecoderImpl::DoIsFramebuffer(GLuint client_id) {
  const Framebuffer* framebuffer =
      GetFramebuffer(client_id);
  return framebuffer && framebuffer->IsValid() && !framebuffer->IsDeleted();
}

bool GLES2DecoderImpl::DoIsProgram(GLuint client_id) {
  // IsProgram is true for programs as soon as they are created, until they are
  // deleted and no longer in use.
  const Program* program = GetProgram(client_id);
  return program != NULL && !program->IsDeleted();
}

bool GLES2DecoderImpl::DoIsRenderbuffer(GLuint client_id) {
  const Renderbuffer* renderbuffer =
      GetRenderbuffer(client_id);
  return renderbuffer && renderbuffer->IsValid() && !renderbuffer->IsDeleted();
}

bool GLES2DecoderImpl::DoIsShader(GLuint client_id) {
  // IsShader is true for shaders as soon as they are created, until they
  // are deleted and not attached to any programs.
  const Shader* shader = GetShader(client_id);
  return shader != NULL && !shader->IsDeleted();
}

bool GLES2DecoderImpl::DoIsTexture(GLuint client_id) {
  const TextureRef* texture_ref = GetTexture(client_id);
  return texture_ref && texture_ref->texture()->IsValid();
}

void GLES2DecoderImpl::DoAttachShader(
    GLuint program_client_id, GLint shader_client_id) {
  Program* program = GetProgramInfoNotShader(
      program_client_id, "glAttachShader");
  if (!program) {
    return;
  }
  Shader* shader = GetShaderInfoNotProgram(shader_client_id, "glAttachShader");
  if (!shader) {
    return;
  }
  if (!program->AttachShader(shader_manager(), shader)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glAttachShader",
        "can not attach more than one shader of the same type.");
    return;
  }
  glAttachShader(program->service_id(), shader->service_id());
}

void GLES2DecoderImpl::DoDetachShader(
    GLuint program_client_id, GLint shader_client_id) {
  Program* program = GetProgramInfoNotShader(
      program_client_id, "glDetachShader");
  if (!program) {
    return;
  }
  Shader* shader = GetShaderInfoNotProgram(shader_client_id, "glDetachShader");
  if (!shader) {
    return;
  }
  if (!program->DetachShader(shader_manager(), shader)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glDetachShader", "shader not attached to program");
    return;
  }
  glDetachShader(program->service_id(), shader->service_id());
}

void GLES2DecoderImpl::DoValidateProgram(GLuint program_client_id) {
  Program* program = GetProgramInfoNotShader(
      program_client_id, "glValidateProgram");
  if (!program) {
    return;
  }
  program->Validate();
}

void GLES2DecoderImpl::GetVertexAttribHelper(
    const VertexAttrib* attrib, GLenum pname, GLint* params) {
  switch (pname) {
    case GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING: {
        Buffer* buffer = attrib->buffer();
        if (buffer && !buffer->IsDeleted()) {
          GLuint client_id;
          buffer_manager()->GetClientId(buffer->service_id(), &client_id);
          *params = client_id;
        }
        break;
      }
    case GL_VERTEX_ATTRIB_ARRAY_ENABLED:
      *params = attrib->enabled();
      break;
    case GL_VERTEX_ATTRIB_ARRAY_SIZE:
      *params = attrib->size();
      break;
    case GL_VERTEX_ATTRIB_ARRAY_STRIDE:
      *params = attrib->gl_stride();
      break;
    case GL_VERTEX_ATTRIB_ARRAY_TYPE:
      *params = attrib->type();
      break;
    case GL_VERTEX_ATTRIB_ARRAY_NORMALIZED:
      *params = attrib->normalized();
      break;
    case GL_VERTEX_ATTRIB_ARRAY_DIVISOR_ANGLE:
      *params = attrib->divisor();
      break;
    default:
      NOTREACHED();
      break;
  }
}

void GLES2DecoderImpl::DoGetTexParameterfv(
    GLenum target, GLenum pname, GLfloat* params) {
  InitTextureMaxAnisotropyIfNeeded(target, pname);
  glGetTexParameterfv(target, pname, params);
}

void GLES2DecoderImpl::DoGetTexParameteriv(
    GLenum target, GLenum pname, GLint* params) {
  InitTextureMaxAnisotropyIfNeeded(target, pname);
  glGetTexParameteriv(target, pname, params);
}

void GLES2DecoderImpl::InitTextureMaxAnisotropyIfNeeded(
    GLenum target, GLenum pname) {
  if (!workarounds().init_texture_max_anisotropy)
    return;
  if (pname != GL_TEXTURE_MAX_ANISOTROPY_EXT ||
      !validators_->texture_parameter.IsValid(pname)) {
    return;
  }

  TextureRef* texture_ref = texture_manager()->GetTextureInfoForTarget(
      &state_, target);
  if (!texture_ref) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glGetTexParamter{fi}v", "unknown texture for target");
    return;
  }
  Texture* texture = texture_ref->texture();
  texture->InitTextureMaxAnisotropyIfNeeded(target);
}

void GLES2DecoderImpl::DoGetVertexAttribfv(
    GLuint index, GLenum pname, GLfloat* params) {
  VertexAttrib* attrib = state_.vertex_attrib_manager->GetVertexAttrib(index);
  if (!attrib) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glGetVertexAttribfv", "index out of range");
    return;
  }
  switch (pname) {
    case GL_CURRENT_VERTEX_ATTRIB: {
      const Vec4& value = state_.attrib_values[index];
      params[0] = value.v[0];
      params[1] = value.v[1];
      params[2] = value.v[2];
      params[3] = value.v[3];
      break;
    }
    default: {
      GLint value = 0;
      GetVertexAttribHelper(attrib, pname, &value);
      *params = static_cast<GLfloat>(value);
      break;
    }
  }
}

void GLES2DecoderImpl::DoGetVertexAttribiv(
    GLuint index, GLenum pname, GLint* params) {
  VertexAttrib* attrib = state_.vertex_attrib_manager->GetVertexAttrib(index);
  if (!attrib) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glGetVertexAttribiv", "index out of range");
    return;
  }
  switch (pname) {
    case GL_CURRENT_VERTEX_ATTRIB: {
      const Vec4& value = state_.attrib_values[index];
      params[0] = static_cast<GLint>(value.v[0]);
      params[1] = static_cast<GLint>(value.v[1]);
      params[2] = static_cast<GLint>(value.v[2]);
      params[3] = static_cast<GLint>(value.v[3]);
      break;
    }
    default:
      GetVertexAttribHelper(attrib, pname, params);
      break;
  }
}

bool GLES2DecoderImpl::SetVertexAttribValue(
    const char* function_name, GLuint index, const GLfloat* value) {
  if (index >= state_.attrib_values.size()) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, function_name, "index out of range");
    return false;
  }
  Vec4& v = state_.attrib_values[index];
  v.v[0] = value[0];
  v.v[1] = value[1];
  v.v[2] = value[2];
  v.v[3] = value[3];
  return true;
}

void GLES2DecoderImpl::DoVertexAttrib1f(GLuint index, GLfloat v0) {
  GLfloat v[4] = { v0, 0.0f, 0.0f, 1.0f, };
  if (SetVertexAttribValue("glVertexAttrib1f", index, v)) {
    glVertexAttrib1f(index, v0);
  }
}

void GLES2DecoderImpl::DoVertexAttrib2f(GLuint index, GLfloat v0, GLfloat v1) {
  GLfloat v[4] = { v0, v1, 0.0f, 1.0f, };
  if (SetVertexAttribValue("glVertexAttrib2f", index, v)) {
    glVertexAttrib2f(index, v0, v1);
  }
}

void GLES2DecoderImpl::DoVertexAttrib3f(
    GLuint index, GLfloat v0, GLfloat v1, GLfloat v2) {
  GLfloat v[4] = { v0, v1, v2, 1.0f, };
  if (SetVertexAttribValue("glVertexAttrib3f", index, v)) {
    glVertexAttrib3f(index, v0, v1, v2);
  }
}

void GLES2DecoderImpl::DoVertexAttrib4f(
    GLuint index, GLfloat v0, GLfloat v1, GLfloat v2, GLfloat v3) {
  GLfloat v[4] = { v0, v1, v2, v3, };
  if (SetVertexAttribValue("glVertexAttrib4f", index, v)) {
    glVertexAttrib4f(index, v0, v1, v2, v3);
  }
}

void GLES2DecoderImpl::DoVertexAttrib1fv(GLuint index, const GLfloat* v) {
  GLfloat t[4] = { v[0], 0.0f, 0.0f, 1.0f, };
  if (SetVertexAttribValue("glVertexAttrib1fv", index, t)) {
    glVertexAttrib1fv(index, v);
  }
}

void GLES2DecoderImpl::DoVertexAttrib2fv(GLuint index, const GLfloat* v) {
  GLfloat t[4] = { v[0], v[1], 0.0f, 1.0f, };
  if (SetVertexAttribValue("glVertexAttrib2fv", index, t)) {
    glVertexAttrib2fv(index, v);
  }
}

void GLES2DecoderImpl::DoVertexAttrib3fv(GLuint index, const GLfloat* v) {
  GLfloat t[4] = { v[0], v[1], v[2], 1.0f, };
  if (SetVertexAttribValue("glVertexAttrib3fv", index, t)) {
    glVertexAttrib3fv(index, v);
  }
}

void GLES2DecoderImpl::DoVertexAttrib4fv(GLuint index, const GLfloat* v) {
  if (SetVertexAttribValue("glVertexAttrib4fv", index, v)) {
    glVertexAttrib4fv(index, v);
  }
}

error::Error GLES2DecoderImpl::HandleVertexAttribPointer(
    uint32 immediate_data_size, const cmds::VertexAttribPointer& c) {

  if (!state_.bound_array_buffer.get() ||
      state_.bound_array_buffer->IsDeleted()) {
    if (state_.vertex_attrib_manager.get() ==
        state_.default_vertex_attrib_manager.get()) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_VALUE, "glVertexAttribPointer", "no array buffer bound");
      return error::kNoError;
    } else if (c.offset != 0) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_VALUE,
          "glVertexAttribPointer", "client side arrays are not allowed");
      return error::kNoError;
    }
  }

  GLuint indx = c.indx;
  GLint size = c.size;
  GLenum type = c.type;
  GLboolean normalized = c.normalized;
  GLsizei stride = c.stride;
  GLsizei offset = c.offset;
  const void* ptr = reinterpret_cast<const void*>(offset);
  if (!validators_->vertex_attrib_type.IsValid(type)) {
    LOCAL_SET_GL_ERROR_INVALID_ENUM("glVertexAttribPointer", type, "type");
    return error::kNoError;
  }
  if (!validators_->vertex_attrib_size.IsValid(size)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glVertexAttribPointer", "size GL_INVALID_VALUE");
    return error::kNoError;
  }
  if (indx >= group_->max_vertex_attribs()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glVertexAttribPointer", "index out of range");
    return error::kNoError;
  }
  if (stride < 0) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glVertexAttribPointer", "stride < 0");
    return error::kNoError;
  }
  if (stride > 255) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glVertexAttribPointer", "stride > 255");
    return error::kNoError;
  }
  if (offset < 0) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glVertexAttribPointer", "offset < 0");
    return error::kNoError;
  }
  GLsizei component_size =
      GLES2Util::GetGLTypeSizeForTexturesAndBuffers(type);
  if (offset % component_size > 0) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glVertexAttribPointer", "offset not valid for type");
    return error::kNoError;
  }
  if (stride % component_size > 0) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glVertexAttribPointer", "stride not valid for type");
    return error::kNoError;
  }
  state_.vertex_attrib_manager
      ->SetAttribInfo(indx,
                      state_.bound_array_buffer.get(),
                      size,
                      type,
                      normalized,
                      stride,
                      stride != 0 ? stride : component_size * size,
                      offset);
  if (type != GL_FIXED) {
    glVertexAttribPointer(indx, size, type, normalized, stride, ptr);
  }
  return error::kNoError;
}

void GLES2DecoderImpl::DoViewport(GLint x, GLint y, GLsizei width,
                                  GLsizei height) {
  state_.viewport_x = x;
  state_.viewport_y = y;
  state_.viewport_width = std::min(width, viewport_max_width_);
  state_.viewport_height = std::min(height, viewport_max_height_);
  glViewport(x, y, width, height);
}

error::Error GLES2DecoderImpl::HandleVertexAttribDivisorANGLE(
    uint32 immediate_data_size, const cmds::VertexAttribDivisorANGLE& c) {
  if (!features().angle_instanced_arrays) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glVertexAttribDivisorANGLE", "function not available");
    return error::kNoError;
  }
  GLuint index = c.index;
  GLuint divisor = c.divisor;
  if (index >= group_->max_vertex_attribs()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE,
        "glVertexAttribDivisorANGLE", "index out of range");
    return error::kNoError;
  }

  state_.vertex_attrib_manager->SetDivisor(
      index,
      divisor);
  glVertexAttribDivisorANGLE(index, divisor);
  return error::kNoError;
}

template <typename pixel_data_type>
static void WriteAlphaData(
    void *pixels, uint32 row_count, uint32 channel_count,
    uint32 alpha_channel_index, uint32 unpadded_row_size,
    uint32 padded_row_size, pixel_data_type alpha_value) {
  DCHECK_GT(channel_count, 0U);
  DCHECK_EQ(unpadded_row_size % sizeof(pixel_data_type), 0U);
  uint32 unpadded_row_size_in_elements =
      unpadded_row_size / sizeof(pixel_data_type);
  DCHECK_EQ(padded_row_size % sizeof(pixel_data_type), 0U);
  uint32 padded_row_size_in_elements =
      padded_row_size / sizeof(pixel_data_type);
  pixel_data_type* dst =
      static_cast<pixel_data_type*>(pixels) + alpha_channel_index;
  for (uint32 yy = 0; yy < row_count; ++yy) {
    pixel_data_type* end = dst + unpadded_row_size_in_elements;
    for (pixel_data_type* d = dst; d < end; d += channel_count) {
      *d = alpha_value;
    }
    dst += padded_row_size_in_elements;
  }
}

void GLES2DecoderImpl::FinishReadPixels(
    const cmds::ReadPixels& c,
    GLuint buffer) {
  TRACE_EVENT0("gpu", "GLES2DecoderImpl::FinishReadPixels");
  GLsizei width = c.width;
  GLsizei height = c.height;
  GLenum format = c.format;
  GLenum type = c.type;
  typedef cmds::ReadPixels::Result Result;
  uint32 pixels_size;
  Result* result = NULL;
  if (c.result_shm_id != 0) {
    result = GetSharedMemoryAs<Result*>(
        c.result_shm_id, c.result_shm_offset, sizeof(*result));
    if (!result) {
      if (buffer != 0) {
        glDeleteBuffersARB(1, &buffer);
      }
      return;
    }
  }
  GLES2Util::ComputeImageDataSizes(
      width, height, format, type, state_.pack_alignment, &pixels_size,
      NULL, NULL);
  void* pixels = GetSharedMemoryAs<void*>(
      c.pixels_shm_id, c.pixels_shm_offset, pixels_size);
  if (!pixels) {
    if (buffer != 0) {
      glDeleteBuffersARB(1, &buffer);
    }
    return;
  }

  if (buffer != 0) {
    glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, buffer);
    void* data;
    if (features().map_buffer_range) {
      data = glMapBufferRange(
          GL_PIXEL_PACK_BUFFER_ARB, 0, pixels_size, GL_MAP_READ_BIT);
    } else {
      data = glMapBuffer(GL_PIXEL_PACK_BUFFER_ARB, GL_READ_ONLY);
    }
    memcpy(pixels, data, pixels_size);
    // GL_PIXEL_PACK_BUFFER_ARB is currently unused, so we don't
    // have to restore the state.
    glUnmapBuffer(GL_PIXEL_PACK_BUFFER_ARB);
    glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, 0);
    glDeleteBuffersARB(1, &buffer);
  }

  if (result != NULL) {
    *result = true;
  }

  GLenum read_format = GetBoundReadFrameBufferInternalFormat();
  uint32 channels_exist = GLES2Util::GetChannelsForFormat(read_format);
  if ((channels_exist & 0x0008) == 0 &&
      workarounds().clear_alpha_in_readpixels) {
    // Set the alpha to 255 because some drivers are buggy in this regard.
    uint32 temp_size;

    uint32 unpadded_row_size;
    uint32 padded_row_size;
    if (!GLES2Util::ComputeImageDataSizes(
            width, 2, format, type, state_.pack_alignment, &temp_size,
            &unpadded_row_size, &padded_row_size)) {
      return;
    }

    uint32 channel_count = 0;
    uint32 alpha_channel = 0;
    switch (format) {
      case GL_RGBA:
      case GL_BGRA_EXT:
        channel_count = 4;
        alpha_channel = 3;
        break;
      case GL_ALPHA:
        channel_count = 1;
        alpha_channel = 0;
        break;
    }

    if (channel_count > 0) {
      switch (type) {
        case GL_UNSIGNED_BYTE:
          WriteAlphaData<uint8>(
              pixels, height, channel_count, alpha_channel, unpadded_row_size,
              padded_row_size, 0xFF);
          break;
        case GL_FLOAT:
          WriteAlphaData<float>(
              pixels, height, channel_count, alpha_channel, unpadded_row_size,
              padded_row_size, 1.0f);
          break;
        case GL_HALF_FLOAT:
          WriteAlphaData<uint16>(
              pixels, height, channel_count, alpha_channel, unpadded_row_size,
              padded_row_size, 0x3C00);
          break;
      }
    }
  }
}


error::Error GLES2DecoderImpl::HandleReadPixels(
    uint32 immediate_data_size, const cmds::ReadPixels& c) {
  TRACE_EVENT0("gpu", "GLES2DecoderImpl::HandleReadPixels");
  error::Error fbo_error = WillAccessBoundFramebufferForRead();
  if (fbo_error != error::kNoError)
    return fbo_error;
  GLint x = c.x;
  GLint y = c.y;
  GLsizei width = c.width;
  GLsizei height = c.height;
  GLenum format = c.format;
  GLenum type = c.type;
  GLboolean async = c.async;
  if (width < 0 || height < 0) {
    LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "glReadPixels", "dimensions < 0");
    return error::kNoError;
  }
  typedef cmds::ReadPixels::Result Result;
  uint32 pixels_size;
  if (!GLES2Util::ComputeImageDataSizes(
      width, height, format, type, state_.pack_alignment, &pixels_size,
      NULL, NULL)) {
    return error::kOutOfBounds;
  }
  void* pixels = GetSharedMemoryAs<void*>(
      c.pixels_shm_id, c.pixels_shm_offset, pixels_size);
  if (!pixels) {
    return error::kOutOfBounds;
  }
  Result* result = NULL;
  if (c.result_shm_id != 0) {
    result = GetSharedMemoryAs<Result*>(
        c.result_shm_id, c.result_shm_offset, sizeof(*result));
    if (!result) {
      return error::kOutOfBounds;
    }
  }

  if (!validators_->read_pixel_format.IsValid(format)) {
    LOCAL_SET_GL_ERROR_INVALID_ENUM("glReadPixels", format, "format");
    return error::kNoError;
  }
  if (!validators_->read_pixel_type.IsValid(type)) {
    LOCAL_SET_GL_ERROR_INVALID_ENUM("glReadPixels", type, "type");
    return error::kNoError;
  }
  if ((format != GL_RGBA && format != GL_BGRA_EXT && format != GL_RGB &&
      format != GL_ALPHA) || type != GL_UNSIGNED_BYTE) {
    // format and type are acceptable enums but not guaranteed to be supported
    // for this framebuffer.  Have to ask gl if they are valid.
    GLint preferred_format = 0;
    DoGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT, &preferred_format);
    GLint preferred_type = 0;
    DoGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE, &preferred_type);
    if (format != static_cast<GLenum>(preferred_format) ||
        type != static_cast<GLenum>(preferred_type)) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_OPERATION, "glReadPixels", "format and type incompatible "
          "with the current read framebuffer");
      return error::kNoError;
    }
  }
  if (width == 0 || height == 0) {
    return error::kNoError;
  }

  // Get the size of the current fbo or backbuffer.
  gfx::Size max_size = GetBoundReadFrameBufferSize();

  int32 max_x;
  int32 max_y;
  if (!SafeAddInt32(x, width, &max_x) || !SafeAddInt32(y, height, &max_y)) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glReadPixels", "dimensions out of range");
    return error::kNoError;
  }

  if (!CheckBoundFramebuffersValid("glReadPixels")) {
    return error::kNoError;
  }

  LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER("glReadPixels");

  ScopedResolvedFrameBufferBinder binder(this, false, true);

  if (x < 0 || y < 0 || max_x > max_size.width() || max_y > max_size.height()) {
    // The user requested an out of range area. Get the results 1 line
    // at a time.
    uint32 temp_size;
    uint32 unpadded_row_size;
    uint32 padded_row_size;
    if (!GLES2Util::ComputeImageDataSizes(
        width, 2, format, type, state_.pack_alignment, &temp_size,
        &unpadded_row_size, &padded_row_size)) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_VALUE, "glReadPixels", "dimensions out of range");
      return error::kNoError;
    }

    GLint dest_x_offset = std::max(-x, 0);
    uint32 dest_row_offset;
    if (!GLES2Util::ComputeImageDataSizes(
        dest_x_offset, 1, format, type, state_.pack_alignment, &dest_row_offset,
        NULL, NULL)) {
      LOCAL_SET_GL_ERROR(
          GL_INVALID_VALUE, "glReadPixels", "dimensions out of range");
      return error::kNoError;
    }

    // Copy each row into the larger dest rect.
    int8* dst = static_cast<int8*>(pixels);
    GLint read_x = std::max(0, x);
    GLint read_end_x = std::max(0, std::min(max_size.width(), max_x));
    GLint read_width = read_end_x - read_x;
    for (GLint yy = 0; yy < height; ++yy) {
      GLint ry = y + yy;

      // Clear the row.
      memset(dst, 0, unpadded_row_size);

      // If the row is in range, copy it.
      if (ry >= 0 && ry < max_size.height() && read_width > 0) {
        glReadPixels(
            read_x, ry, read_width, 1, format, type, dst + dest_row_offset);
      }
      dst += padded_row_size;
    }
  } else {
    if (async && features().use_async_readpixels) {
      GLuint buffer;
      glGenBuffersARB(1, &buffer);
      glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, buffer);
      glBufferData(GL_PIXEL_PACK_BUFFER_ARB, pixels_size, NULL, GL_STREAM_READ);
      GLenum error = glGetError();
      if (error == GL_NO_ERROR) {
        glReadPixels(x, y, width, height, format, type, 0);
        pending_readpixel_fences_.push(linked_ptr<FenceCallback>(
            new FenceCallback()));
        WaitForReadPixels(base::Bind(
            &GLES2DecoderImpl::FinishReadPixels,
            base::internal::SupportsWeakPtrBase::StaticAsWeakPtr
            <GLES2DecoderImpl>(this),
            c, buffer));
        glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, 0);
        return error::kNoError;
      } else {
        // On error, unbind pack buffer and fall through to sync readpixels
        glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, 0);
      }
    }
    glReadPixels(x, y, width, height, format, type, pixels);
  }
  GLenum error = LOCAL_PEEK_GL_ERROR("glReadPixels");
  if (error == GL_NO_ERROR) {
    if (result != NULL) {
      *result = true;
    }
    FinishReadPixels(c, 0);
  }

  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandlePixelStorei(
    uint32 immediate_data_size, const cmds::PixelStorei& c) {
  GLenum pname = c.pname;
  GLenum param = c.param;
  if (!validators_->pixel_store.IsValid(pname)) {
    LOCAL_SET_GL_ERROR_INVALID_ENUM("glPixelStorei", pname, "pname");
    return error::kNoError;
  }
  switch (pname) {
    case GL_PACK_ALIGNMENT:
    case GL_UNPACK_ALIGNMENT:
        if (!validators_->pixel_store_alignment.IsValid(param)) {
            LOCAL_SET_GL_ERROR(
                GL_INVALID_VALUE, "glPixelStorei", "param GL_INVALID_VALUE");
            return error::kNoError;
        }
        break;
    case GL_UNPACK_FLIP_Y_CHROMIUM:
        unpack_flip_y_ = (param != 0);
        return error::kNoError;
    case GL_UNPACK_PREMULTIPLY_ALPHA_CHROMIUM:
        unpack_premultiply_alpha_ = (param != 0);
        return error::kNoError;
    case GL_UNPACK_UNPREMULTIPLY_ALPHA_CHROMIUM:
        unpack_unpremultiply_alpha_ = (param != 0);
        return error::kNoError;
    default:
        break;
  }
  glPixelStorei(pname, param);
  switch (pname) {
    case GL_PACK_ALIGNMENT:
        state_.pack_alignment = param;
        break;
    case GL_PACK_REVERSE_ROW_ORDER_ANGLE:
        state_.pack_reverse_row_order = (param != 0);
        break;
    case GL_UNPACK_ALIGNMENT:
        state_.unpack_alignment = param;
        break;
    default:
        // Validation should have prevented us from getting here.
        NOTREACHED();
        break;
  }
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandlePostSubBufferCHROMIUM(
    uint32 immediate_data_size, const cmds::PostSubBufferCHROMIUM& c) {
  TRACE_EVENT0("gpu", "GLES2DecoderImpl::HandlePostSubBufferCHROMIUM");
  {
    TRACE_EVENT_SYNTHETIC_DELAY("gpu.PresentingFrame");
  }
  if (!supports_post_sub_buffer_) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION,
        "glPostSubBufferCHROMIUM", "command not supported by surface");
    return error::kNoError;
  }
  bool is_tracing;
  TRACE_EVENT_CATEGORY_GROUP_ENABLED(TRACE_DISABLED_BY_DEFAULT("gpu.debug"),
                                     &is_tracing);
  if (is_tracing) {
    bool is_offscreen = !!offscreen_target_frame_buffer_.get();
    ScopedFrameBufferBinder binder(this, GetBackbufferServiceId());
    gpu_state_tracer_->TakeSnapshotWithCurrentFramebuffer(
        is_offscreen ? offscreen_size_ : surface_->GetSize());
  }
  if (surface_->PostSubBuffer(c.x, c.y, c.width, c.height)) {
    return error::kNoError;
  } else {
    LOG(ERROR) << "Context lost because PostSubBuffer failed.";
    return error::kLostContext;
  }
}

error::Error GLES2DecoderImpl::HandleScheduleOverlayPlaneCHROMIUM(
    uint32 immediate_data_size,
    const cmds::ScheduleOverlayPlaneCHROMIUM& c) {
  NOTIMPLEMENTED() << "Overlay supported isn't finished.";
  LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION,
                     "glScheduleOverlayPlaneCHROMIUM",
                     "function not implemented");
  return error::kNoError;
}

error::Error GLES2DecoderImpl::GetAttribLocationHelper(
    GLuint client_id, uint32 location_shm_id, uint32 location_shm_offset,
    const std::string& name_str) {
  if (!StringIsValidForGLES(name_str.c_str())) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glGetAttribLocation", "Invalid character");
    return error::kNoError;
  }
  Program* program = GetProgramInfoNotShader(
      client_id, "glGetAttribLocation");
  if (!program) {
    return error::kNoError;
  }
  if (!program->IsValid()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, "glGetAttribLocation", "program not linked");
    return error::kNoError;
  }
  GLint* location = GetSharedMemoryAs<GLint*>(
      location_shm_id, location_shm_offset, sizeof(GLint));
  if (!location) {
    return error::kOutOfBounds;
  }
  // Require the client to init this incase the context is lost and we are no
  // longer executing commands.
  if (*location != -1) {
    return error::kGenericError;
  }
  *location = program->GetAttribLocation(name_str);
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleGetAttribLocation(
    uint32 immediate_data_size, const cmds::GetAttribLocation& c) {
  Bucket* bucket = GetBucket(c.name_bucket_id);
  if (!bucket) {
    return error::kInvalidArguments;
  }
  std::string name_str;
  if (!bucket->GetAsString(&name_str)) {
    return error::kInvalidArguments;
  }
  return GetAttribLocationHelper(
    c.program, c.location_shm_id, c.location_shm_offset, name_str);
}

error::Error GLES2DecoderImpl::GetUniformLocationHelper(
    GLuint client_id, uint32 location_shm_id, uint32 location_shm_offset,
    const std::string& name_str) {
  if (!StringIsValidForGLES(name_str.c_str())) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_VALUE, "glGetUniformLocation", "Invalid character");
    return error::kNoError;
  }
  Program* program = GetProgramInfoNotShader(
      client_id, "glGetUniformLocation");
  if (!program) {
    return error::kNoError;
  }
  if (!program->IsValid()) {
    LOCAL_SET_GL_ERROR(
        GL_INVALID_OPERATION, "glGetUniformLocation", "program not linked");
    return error::kNoError;
  }
  GLint* location = GetSharedMemoryAs<GLint*>(
      location_shm_id, location_shm_offset, sizeof(GLint));
  if (!location) {
    return error::kOutOfBounds;
  }
  // Require the client to init this incase the context is lost an we are no
  // longer executing commands.
  if (*location != -1) {
    return error::kGenericError;
  }
  *location = program->GetUniformFakeLocation(name_str);
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleGetUniformLocation(
    uint32 immediate_data_size, const cmds::GetUniformLocation& c) {
  Bucket* bucket = GetBucket(c.name_bucket_id);
  if (!bucket) {
    return error::kInvalidArguments;
  }
  std::string name_str;
  if (!bucket->GetAsString(&name_str)) {
    return error::kInvalidArguments;
  }
  return GetUniformLocationHelper(
    c.program, c.location_shm_id, c.location_shm_offset, name_str);
}

error::Error GLES2DecoderImpl::HandleGetString(
    uint32 immediate_data_size, const cmds::GetString& c) {
  GLenum name = static_cast<GLenum>(c.name);
  if (!validators_->string_type.IsValid(name)) {
    LOCAL_SET_GL_ERROR_INVALID_ENUM("glGetString", name, "name");
    return error::kNoError;
  }
  const char* str = reinterpret_cast<const char*>(glGetString(name));
  std::string extensions;
  switch (name) {
    case GL_VERSION:
      str = "OpenGL ES 2.0 Chromium";
      break;
    case GL_SHADING_LANGUAGE_VERSION:
      str = "OpenGL ES GLSL ES 1.0 Chromium";
      break;
    case GL_RENDERER:
    case GL_VENDOR:
      // Return the unmasked VENDOR/RENDERER string for WebGL contexts.
      // They are used by WEBGL_debug_renderer_info.
      if (!force_webgl_glsl_validation_)
        str = "Chromium";
      break;
    case GL_EXTENSIONS:
      {
        // For WebGL contexts, strip out the OES derivatives and
        // EXT frag depth extensions if they have not been enabled.
        if (force_webgl_glsl_validation_) {
          extensions = feature_info_->extensions();
          if (!derivatives_explicitly_enabled_) {
            size_t offset = extensions.find(kOESDerivativeExtension);
            if (std::string::npos != offset) {
              extensions.replace(offset, arraysize(kOESDerivativeExtension),
                                 std::string());
            }
          }
          if (!frag_depth_explicitly_enabled_) {
            size_t offset = extensions.find(kEXTFragDepthExtension);
            if (std::string::npos != offset) {
              extensions.replace(offset, arraysize(kEXTFragDepthExtension),
                                 std::string());
            }
          }
          if (!draw_buffers_explicitly_enabled_) {
            size_t offset = extensions.find(kEXTDrawBuffersExtension);
            if (std::string::npos != offset) {
              extensions.replace(offset, arraysize(kEXTDrawBuffersExtension),
                                 std::string());
            }
          }
          if (!shader_texture_lod_explicitly_enabled_) {
            size_t offset = extensions.find(kEXTShaderTextureLodExtension);
            if (std::string::npos != offset) {
              extensions.replace(offset,
                                 arraysize(kEXTShaderTextureLodExtension),
                                 std::string());
            }
          }
        } else {
          extensions = feature_info_->extensions().c_str();
        }
        if (supports_post_sub_buffer_)
          extensions += " GL_CHROMIUM_post_sub_buffer";
        str = extensions.c_str();
      }
      break;
    default:
      break;
  }
  Bucket* bucket = CreateBucket(c.bucket_id);
  bucket->SetFromString(str);
  return error::kNoError;
}

error::Error GLES2DecoderImpl::HandleBufferData(
    uint32 immediate_data_size, const cmds::BufferData& c) {
  GLenum target = static_cast<GLenum>(c.target);
  GLsizeiptr size = static_cast<GLsizeiptr>(c.size);
  uint32 data_shm_id = static_cast<uint32>(c.data_shm_id);
  uint32 data_shm_offset = static_cast<uint32>(c.data_shm_offset);
  GLenum usage = static_cast<GLenum>(c.usage);
  const void* data = NULL;
  if (data_shm_id != 0 || data_shm_offset != 0) {
    data = GetSharedMemoryAs<const void*>(data_shm_id, data_shm_offset, size);
    if (!data) {
      return error::kOutOfBounds;
    }
  }
  buffer_manager()->ValidateAndDoBufferData(&state_, target, size, data, usage);
  return error::kNoError;
}

void GLES2DecoderImpl::DoBufferSubData(
  GLenum target, GLintptr offset, GLsizeiptr size, const GLvoid * data) {
  // Just delegate it. Some validation is actually done before this.
  buffer_manager()->ValidateAndDoBufferSubData(
      &state_, target, offset, size, data);
}

bool GLES2DecoderImpl::ClearLevel(
    unsigned service_id,
    unsigned bind_target,
    unsigned target,
    int level,
    unsigned internal_format,
    unsigned format,
    unsigned type,
    int width,
    int height,
    bool is_texture_immutable) {
  uint32 channels = GLES2Util::GetChannelsForFormat(format);
  if (feature_info_->feature_flags().angle_depth_texture &&
      (channels & GLES2Util::kDepth) != 0) {
    // It's a depth format and ANGLE doesn't allow texImage2D or texSubImage2D
    // on depth formats.
    GLuint fb = 0;
    glGenFramebuffersEXT(1, &fb);
    glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, fb);

    bool have_stencil = (channels & GLES2Util::kStencil) != 0;
    GLenum attachment = have_stencil ? GL_DEPTH_STENCIL_ATTACHMENT :
                                       GL_DEPTH_ATTACHMENT;

    glFramebufferTexture2DEXT(
        GL_DRAW_FRAMEBUFFER_EXT, attachment, target, service_id, level);
    // ANGLE promises a depth only attachment ok.
    if (glCheckFramebufferStatusEXT(GL_DRAW_FRAMEBUFFER_EXT) !=
        GL_FRAMEBUFFER_COMPLETE) {
      return false;
    }
    glClearStencil(0);
    state_.SetDeviceStencilMaskSeparate(GL_FRONT, -1);
    state_.SetDeviceStencilMaskSeparate(GL_BACK, -1);
    glClearDepth(1.0f);
    state_.SetDeviceDepthMask(GL_TRUE);
    state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, false);
    glClear(GL_DEPTH_BUFFER_BIT | (have_stencil ? GL_STENCIL_BUFFER_BIT : 0));