xref: /external/chromium/chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc

// Copyright (c) 2011 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 "chrome/browser/ui/gtk/tabs/tab_strip_gtk.h"

#include <algorithm>

#include "base/i18n/rtl.h"
#include "base/string_util.h"
#include "base/utf_string_conversions.h"
#include "chrome/browser/autocomplete/autocomplete.h"
#include "chrome/browser/autocomplete/autocomplete_classifier.h"
#include "chrome/browser/autocomplete/autocomplete_match.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/tabs/tab_strip_model_delegate.h"
#include "chrome/browser/themes/theme_service.h"
#include "chrome/browser/ui/browser.h"
#include "chrome/browser/ui/browser_navigator.h"
#include "chrome/browser/ui/gtk/browser_window_gtk.h"
#include "chrome/browser/ui/gtk/custom_button.h"
#include "chrome/browser/ui/gtk/gtk_theme_service.h"
#include "chrome/browser/ui/gtk/gtk_util.h"
#include "chrome/browser/ui/gtk/tabs/dragged_tab_controller_gtk.h"
#include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
#include "content/browser/tab_contents/tab_contents.h"
#include "content/common/notification_service.h"
#include "content/common/notification_type.h"
#include "grit/app_resources.h"
#include "grit/theme_resources.h"
#include "ui/base/animation/animation_delegate.h"
#include "ui/base/animation/slide_animation.h"
#include "ui/base/dragdrop/gtk_dnd_util.h"
#include "ui/base/resource/resource_bundle.h"
#include "ui/gfx/gtk_util.h"
#include "ui/gfx/point.h"

namespace {

const int kDefaultAnimationDurationMs = 100;
const int kResizeLayoutAnimationDurationMs = 166;
const int kReorderAnimationDurationMs = 166;
const int kAnimateToBoundsDurationMs = 150;
const int kMiniTabAnimationDurationMs = 150;

const int kNewTabButtonHOffset = -5;
const int kNewTabButtonVOffset = 5;

// The delay between when the mouse leaves the tabstrip and the resize animation
// is started.
const int kResizeTabsTimeMs = 300;

// The range outside of the tabstrip where the pointer must enter/leave to
// start/stop the resize animation.
const int kTabStripAnimationVSlop = 40;

const int kHorizontalMoveThreshold = 16;  // pixels

// The horizontal offset from one tab to the next, which results in overlapping
// tabs.
const int kTabHOffset = -16;

// A linux specific menu item for toggling window decorations.
const int kShowWindowDecorationsCommand = 200;

// Size of the drop indicator.
static int drop_indicator_width;
static int drop_indicator_height;

inline int Round(double x) {
  return static_cast<int>(x + 0.5);
}

// widget->allocation is not guaranteed to be set.  After window creation,
// we pick up the normal bounds by connecting to the configure-event signal.
gfx::Rect GetInitialWidgetBounds(GtkWidget* widget) {
  GtkRequisition request;
  gtk_widget_size_request(widget, &request);
  return gfx::Rect(0, 0, request.width, request.height);
}

// Sort rectangles based on their x position.  We don't care about y position
// so we don't bother breaking ties.
int CompareGdkRectangles(const void* p1, const void* p2) {
  int p1_x = static_cast<const GdkRectangle*>(p1)->x;
  int p2_x = static_cast<const GdkRectangle*>(p2)->x;
  if (p1_x < p2_x)
    return -1;
  else if (p1_x == p2_x)
    return 0;
  return 1;
}

bool GdkRectMatchesTabFaviconBounds(const GdkRectangle& gdk_rect, TabGtk* tab) {
  gfx::Rect favicon_bounds = tab->favicon_bounds();
  return gdk_rect.x == favicon_bounds.x() + tab->x() &&
      gdk_rect.y == favicon_bounds.y() + tab->y() &&
      gdk_rect.width == favicon_bounds.width() &&
      gdk_rect.height == favicon_bounds.height();
}

}  // namespace

////////////////////////////////////////////////////////////////////////////////
//
// TabAnimation
//
//  A base class for all TabStrip animations.
//
class TabStripGtk::TabAnimation : public ui::AnimationDelegate {
 public:
  friend class TabStripGtk;

  // Possible types of animation.
  enum Type {
    INSERT,
    REMOVE,
    MOVE,
    RESIZE,
    MINI,
    MINI_MOVE
  };

  TabAnimation(TabStripGtk* tabstrip, Type type)
      : tabstrip_(tabstrip),
        animation_(this),
        start_selected_width_(0),
        start_unselected_width_(0),
        end_selected_width_(0),
        end_unselected_width_(0),
        layout_on_completion_(false),
        type_(type) {
  }
  virtual ~TabAnimation() {}

  Type type() const { return type_; }

  void Start() {
    animation_.SetSlideDuration(GetDuration());
    animation_.SetTweenType(ui::Tween::EASE_OUT);
    if (!animation_.IsShowing()) {
      animation_.Reset();
      animation_.Show();
    }
  }

  void Stop() {
    animation_.Stop();
  }

  void set_layout_on_completion(bool layout_on_completion) {
    layout_on_completion_ = layout_on_completion;
  }

  // Retrieves the width for the Tab at the specified index if an animation is
  // active.
  static double GetCurrentTabWidth(TabStripGtk* tabstrip,
                                   TabStripGtk::TabAnimation* animation,
                                   int index) {
    TabGtk* tab = tabstrip->GetTabAt(index);
    double tab_width;
    if (tab->mini()) {
      tab_width = TabGtk::GetMiniWidth();
    } else {
      double unselected, selected;
      tabstrip->GetCurrentTabWidths(&unselected, &selected);
      tab_width = tab->IsSelected() ? selected : unselected;
    }

    if (animation) {
      double specified_tab_width = animation->GetWidthForTab(index);
      if (specified_tab_width != -1)
        tab_width = specified_tab_width;
    }

    return tab_width;
  }

  // Overridden from ui::AnimationDelegate:
  virtual void AnimationProgressed(const ui::Animation* animation) {
    tabstrip_->AnimationLayout(end_unselected_width_);
  }

  virtual void AnimationEnded(const ui::Animation* animation) {
    tabstrip_->FinishAnimation(this, layout_on_completion_);
    // This object is destroyed now, so we can't do anything else after this.
  }

  virtual void AnimationCanceled(const ui::Animation* animation) {
    AnimationEnded(animation);
  }

  // Returns the gap before the tab at the specified index. Subclass if during
  // an animation you need to insert a gap before a tab.
  virtual double GetGapWidth(int index) {
    return 0;
  }

 protected:
  // Returns the duration of the animation.
  virtual int GetDuration() const {
    return kDefaultAnimationDurationMs;
  }

  // Subclasses override to return the width of the Tab at the specified index
  // at the current animation frame. -1 indicates the default width should be
  // used for the Tab.
  virtual double GetWidthForTab(int index) const {
    return -1;  // Use default.
  }

  // Figure out the desired start and end widths for the specified pre- and
  // post- animation tab counts.
  void GenerateStartAndEndWidths(int start_tab_count, int end_tab_count,
                                 int start_mini_count,
                                 int end_mini_count) {
    tabstrip_->GetDesiredTabWidths(start_tab_count, start_mini_count,
                                   &start_unselected_width_,
                                   &start_selected_width_);
    double standard_tab_width =
        static_cast<double>(TabRendererGtk::GetStandardSize().width());

    if ((end_tab_count - start_tab_count) > 0 &&
        start_unselected_width_ < standard_tab_width) {
      double minimum_tab_width = static_cast<double>(
          TabRendererGtk::GetMinimumUnselectedSize().width());
      start_unselected_width_ -= minimum_tab_width / start_tab_count;
    }

    tabstrip_->GenerateIdealBounds();
    tabstrip_->GetDesiredTabWidths(end_tab_count, end_mini_count,
                                   &end_unselected_width_,
                                   &end_selected_width_);
  }

  TabStripGtk* tabstrip_;
  ui::SlideAnimation animation_;

  double start_selected_width_;
  double start_unselected_width_;
  double end_selected_width_;
  double end_unselected_width_;

 private:
  // True if a complete re-layout is required upon completion of the animation.
  // Subclasses set this if they don't perform a complete layout
  // themselves and canceling the animation may leave the strip in an
  // inconsistent state.
  bool layout_on_completion_;

  const Type type_;

  DISALLOW_COPY_AND_ASSIGN(TabAnimation);
};

////////////////////////////////////////////////////////////////////////////////

// Handles insertion of a Tab at |index|.
class InsertTabAnimation : public TabStripGtk::TabAnimation {
 public:
  explicit InsertTabAnimation(TabStripGtk* tabstrip, int index)
      : TabAnimation(tabstrip, INSERT),
        index_(index) {
    int tab_count = tabstrip->GetTabCount();
    int end_mini_count = tabstrip->GetMiniTabCount();
    int start_mini_count = end_mini_count;
    if (index < end_mini_count)
      start_mini_count--;
    GenerateStartAndEndWidths(tab_count - 1, tab_count, start_mini_count,
                              end_mini_count);
  }
  virtual ~InsertTabAnimation() {}

 protected:
  // Overridden from TabStripGtk::TabAnimation:
  virtual double GetWidthForTab(int index) const {
    if (index == index_) {
      bool is_selected = tabstrip_->model()->active_index() == index;
      double start_width, target_width;
      if (index < tabstrip_->GetMiniTabCount()) {
        start_width = TabGtk::GetMinimumSelectedSize().width();
        target_width = TabGtk::GetMiniWidth();
      } else {
        target_width =
            is_selected ? end_unselected_width_ : end_selected_width_;
        start_width =
            is_selected ? TabGtk::GetMinimumSelectedSize().width() :
                          TabGtk::GetMinimumUnselectedSize().width();
      }

      double delta = target_width - start_width;
      if (delta > 0)
        return start_width + (delta * animation_.GetCurrentValue());

      return start_width;
    }

    if (tabstrip_->GetTabAt(index)->mini())
      return TabGtk::GetMiniWidth();

    if (tabstrip_->GetTabAt(index)->IsSelected()) {
      double delta = end_selected_width_ - start_selected_width_;
      return start_selected_width_ + (delta * animation_.GetCurrentValue());
    }

    double delta = end_unselected_width_ - start_unselected_width_;
    return start_unselected_width_ + (delta * animation_.GetCurrentValue());
  }

 private:
  int index_;

  DISALLOW_COPY_AND_ASSIGN(InsertTabAnimation);
};

////////////////////////////////////////////////////////////////////////////////

// Handles removal of a Tab from |index|
class RemoveTabAnimation : public TabStripGtk::TabAnimation {
 public:
  RemoveTabAnimation(TabStripGtk* tabstrip, int index, TabContents* contents)
      : TabAnimation(tabstrip, REMOVE),
        index_(index) {
    int tab_count = tabstrip->GetTabCount();
    int start_mini_count = tabstrip->GetMiniTabCount();
    int end_mini_count = start_mini_count;
    if (index < start_mini_count)
      end_mini_count--;
    GenerateStartAndEndWidths(tab_count, tab_count - 1, start_mini_count,
                              end_mini_count);
    // If the last non-mini-tab is being removed we force a layout on
    // completion. This is necessary as the value returned by GetTabHOffset
    // changes once the tab is actually removed (which happens at the end of
    // the animation), and unless we layout GetTabHOffset won't be called after
    // the removal.
    // We do the same when the last mini-tab is being removed for the same
    // reason.
    set_layout_on_completion(start_mini_count > 0 &&
                             (end_mini_count == 0 ||
                              (start_mini_count == end_mini_count &&
                               tab_count == start_mini_count + 1)));
  }

  virtual ~RemoveTabAnimation() {}

  // Returns the index of the tab being removed.
  int index() const { return index_; }

 protected:
  // Overridden from TabStripGtk::TabAnimation:
  virtual double GetWidthForTab(int index) const {
    TabGtk* tab = tabstrip_->GetTabAt(index);

    if (index == index_) {
      // The tab(s) being removed are gradually shrunken depending on the state
      // of the animation.
      if (tab->mini()) {
        return animation_.CurrentValueBetween(TabGtk::GetMiniWidth(),
                                              -kTabHOffset);
      }

      // Removed animated Tabs are never selected.
      double start_width = start_unselected_width_;
      // Make sure target_width is at least abs(kTabHOffset), otherwise if
      // less than kTabHOffset during layout tabs get negatively offset.
      double target_width =
          std::max(abs(kTabHOffset),
                   TabGtk::GetMinimumUnselectedSize().width() + kTabHOffset);
      return animation_.CurrentValueBetween(start_width, target_width);
    }

    if (tab->mini())
      return TabGtk::GetMiniWidth();

    if (tabstrip_->available_width_for_tabs_ != -1 &&
        index_ != tabstrip_->GetTabCount() - 1) {
      return TabStripGtk::TabAnimation::GetWidthForTab(index);
    }

    // All other tabs are sized according to the start/end widths specified at
    // the start of the animation.
    if (tab->IsSelected()) {
      double delta = end_selected_width_ - start_selected_width_;
      return start_selected_width_ + (delta * animation_.GetCurrentValue());
    }

    double delta = end_unselected_width_ - start_unselected_width_;
    return start_unselected_width_ + (delta * animation_.GetCurrentValue());
  }

  virtual void AnimationEnded(const ui::Animation* animation) {
    tabstrip_->RemoveTabAt(index_);
    TabStripGtk::TabAnimation::AnimationEnded(animation);
  }

 private:
  int index_;

  DISALLOW_COPY_AND_ASSIGN(RemoveTabAnimation);
};

////////////////////////////////////////////////////////////////////////////////

// Handles the movement of a Tab from one position to another.
class MoveTabAnimation : public TabStripGtk::TabAnimation {
 public:
  MoveTabAnimation(TabStripGtk* tabstrip, int tab_a_index, int tab_b_index)
      : TabAnimation(tabstrip, MOVE),
        start_tab_a_bounds_(tabstrip_->GetIdealBounds(tab_b_index)),
        start_tab_b_bounds_(tabstrip_->GetIdealBounds(tab_a_index)) {
    tab_a_ = tabstrip_->GetTabAt(tab_a_index);
    tab_b_ = tabstrip_->GetTabAt(tab_b_index);

    // Since we don't do a full TabStrip re-layout, we need to force a full
    // layout upon completion since we're not guaranteed to be in a good state
    // if for example the animation is canceled.
    set_layout_on_completion(true);
  }
  virtual ~MoveTabAnimation() {}

  // Overridden from ui::AnimationDelegate:
  virtual void AnimationProgressed(const ui::Animation* animation) {
    // Position Tab A
    double distance = start_tab_b_bounds_.x() - start_tab_a_bounds_.x();
    double delta = distance * animation_.GetCurrentValue();
    double new_x = start_tab_a_bounds_.x() + delta;
    gfx::Rect bounds(Round(new_x), start_tab_a_bounds_.y(), tab_a_->width(),
        tab_a_->height());
    tabstrip_->SetTabBounds(tab_a_, bounds);

    // Position Tab B
    distance = start_tab_a_bounds_.x() - start_tab_b_bounds_.x();
    delta = distance * animation_.GetCurrentValue();
    new_x = start_tab_b_bounds_.x() + delta;
    bounds = gfx::Rect(Round(new_x), start_tab_b_bounds_.y(), tab_b_->width(),
        tab_b_->height());
    tabstrip_->SetTabBounds(tab_b_, bounds);
  }

 protected:
  // Overridden from TabStripGtk::TabAnimation:
  virtual int GetDuration() const { return kReorderAnimationDurationMs; }

 private:
  // The two tabs being exchanged.
  TabGtk* tab_a_;
  TabGtk* tab_b_;

  // ...and their bounds.
  gfx::Rect start_tab_a_bounds_;
  gfx::Rect start_tab_b_bounds_;

  DISALLOW_COPY_AND_ASSIGN(MoveTabAnimation);
};

////////////////////////////////////////////////////////////////////////////////

// Handles the animated resize layout of the entire TabStrip from one width
// to another.
class ResizeLayoutAnimation : public TabStripGtk::TabAnimation {
 public:
  explicit ResizeLayoutAnimation(TabStripGtk* tabstrip)
      : TabAnimation(tabstrip, RESIZE) {
    int tab_count = tabstrip->GetTabCount();
    int mini_tab_count = tabstrip->GetMiniTabCount();
    GenerateStartAndEndWidths(tab_count, tab_count, mini_tab_count,
                              mini_tab_count);
    InitStartState();
  }
  virtual ~ResizeLayoutAnimation() {}

  // Overridden from ui::AnimationDelegate:
  virtual void AnimationEnded(const ui::Animation* animation) {
    tabstrip_->needs_resize_layout_ = false;
    TabStripGtk::TabAnimation::AnimationEnded(animation);
  }

 protected:
  // Overridden from TabStripGtk::TabAnimation:
  virtual int GetDuration() const {
    return kResizeLayoutAnimationDurationMs;
  }

  virtual double GetWidthForTab(int index) const {
    TabGtk* tab = tabstrip_->GetTabAt(index);

    if (tab->mini())
      return TabGtk::GetMiniWidth();

    if (tab->IsSelected()) {
      return animation_.CurrentValueBetween(start_selected_width_,
                                            end_selected_width_);
    }

    return animation_.CurrentValueBetween(start_unselected_width_,
                                          end_unselected_width_);
  }

 private:
  // We need to start from the current widths of the Tabs as they were last
  // laid out, _not_ the last known good state, which is what'll be done if we
  // don't measure the Tab sizes here and just go with the default TabAnimation
  // behavior...
  void InitStartState() {
    for (int i = 0; i < tabstrip_->GetTabCount(); ++i) {
      TabGtk* current_tab = tabstrip_->GetTabAt(i);
      if (!current_tab->mini()) {
        if (current_tab->IsSelected()) {
          start_selected_width_ = current_tab->width();
        } else {
          start_unselected_width_ = current_tab->width();
        }
      }
    }
  }

  DISALLOW_COPY_AND_ASSIGN(ResizeLayoutAnimation);
};

// Handles a tabs mini-state changing while the tab does not change position
// in the model.
class MiniTabAnimation : public TabStripGtk::TabAnimation {
 public:
  explicit MiniTabAnimation(TabStripGtk* tabstrip, int index)
      : TabAnimation(tabstrip, MINI),
        index_(index) {
    int tab_count = tabstrip->GetTabCount();
    int start_mini_count = tabstrip->GetMiniTabCount();
    int end_mini_count = start_mini_count;
    if (tabstrip->GetTabAt(index)->mini())
      start_mini_count--;
    else
      start_mini_count++;
    tabstrip_->GetTabAt(index)->set_animating_mini_change(true);
    GenerateStartAndEndWidths(tab_count, tab_count, start_mini_count,
                              end_mini_count);
  }

 protected:
  // Overridden from TabStripGtk::TabAnimation:
  virtual int GetDuration() const {
    return kMiniTabAnimationDurationMs;
  }

  virtual double GetWidthForTab(int index) const {
    TabGtk* tab = tabstrip_->GetTabAt(index);

    if (index == index_) {
      if (tab->mini()) {
        return animation_.CurrentValueBetween(
            start_selected_width_,
            static_cast<double>(TabGtk::GetMiniWidth()));
      } else {
        return animation_.CurrentValueBetween(
            static_cast<double>(TabGtk::GetMiniWidth()),
            end_selected_width_);
      }
    } else if (tab->mini()) {
      return TabGtk::GetMiniWidth();
    }

    if (tab->IsSelected()) {
      return animation_.CurrentValueBetween(start_selected_width_,
                                            end_selected_width_);
    }

    return animation_.CurrentValueBetween(start_unselected_width_,
                                          end_unselected_width_);
  }

 private:
  // Index of the tab whose mini-state changed.
  int index_;

  DISALLOW_COPY_AND_ASSIGN(MiniTabAnimation);
};

////////////////////////////////////////////////////////////////////////////////

// Handles the animation when a tabs mini-state changes and the tab moves as a
// result.
class MiniMoveAnimation : public TabStripGtk::TabAnimation {
 public:
  explicit MiniMoveAnimation(TabStripGtk* tabstrip,
                             int from_index,
                             int to_index,
                             const gfx::Rect& start_bounds)
      : TabAnimation(tabstrip, MINI_MOVE),
        tab_(tabstrip->GetTabAt(to_index)),
        start_bounds_(start_bounds),
        from_index_(from_index),
        to_index_(to_index) {
    int tab_count = tabstrip->GetTabCount();
    int start_mini_count = tabstrip->GetMiniTabCount();
    int end_mini_count = start_mini_count;
    if (tabstrip->GetTabAt(to_index)->mini())
      start_mini_count--;
    else
      start_mini_count++;
    GenerateStartAndEndWidths(tab_count, tab_count, start_mini_count,
                              end_mini_count);
    target_bounds_ = tabstrip->GetIdealBounds(to_index);
    tab_->set_animating_mini_change(true);
  }

  // Overridden from ui::AnimationDelegate:
  virtual void AnimationProgressed(const ui::Animation* animation) {
    // Do the normal layout.
    TabAnimation::AnimationProgressed(animation);

    // Then special case the position of the tab being moved.
    int x = animation_.CurrentValueBetween(start_bounds_.x(),
                                           target_bounds_.x());
    int width = animation_.CurrentValueBetween(start_bounds_.width(),
                                               target_bounds_.width());
    gfx::Rect tab_bounds(x, start_bounds_.y(), width,
                         start_bounds_.height());
    tabstrip_->SetTabBounds(tab_, tab_bounds);
  }

  virtual void AnimationEnded(const ui::Animation* animation) {
    tabstrip_->needs_resize_layout_ = false;
    TabStripGtk::TabAnimation::AnimationEnded(animation);
  }

  virtual double GetGapWidth(int index) {
    if (to_index_ < from_index_) {
      // The tab was made mini.
      if (index == to_index_) {
        double current_size =
            animation_.CurrentValueBetween(0, target_bounds_.width());
        if (current_size < -kTabHOffset)
          return -(current_size + kTabHOffset);
      } else if (index == from_index_ + 1) {
        return animation_.CurrentValueBetween(start_bounds_.width(), 0);
      }
    } else {
      // The tab was was made a normal tab.
      if (index == from_index_) {
        return animation_.CurrentValueBetween(
            TabGtk::GetMiniWidth() + kTabHOffset, 0);
      }
    }
    return 0;
  }

 protected:
  // Overridden from TabStripGtk::TabAnimation:
  virtual int GetDuration() const { return kReorderAnimationDurationMs; }

  virtual double GetWidthForTab(int index) const {
    TabGtk* tab = tabstrip_->GetTabAt(index);

    if (index == to_index_)
      return animation_.CurrentValueBetween(0, target_bounds_.width());

    if (tab->mini())
      return TabGtk::GetMiniWidth();

    if (tab->IsSelected()) {
      return animation_.CurrentValueBetween(start_selected_width_,
                                            end_selected_width_);
    }

    return animation_.CurrentValueBetween(start_unselected_width_,
                                          end_unselected_width_);
  }

 private:
  // The tab being moved.
  TabGtk* tab_;

  // Initial bounds of tab_.
  gfx::Rect start_bounds_;

  // Target bounds.
  gfx::Rect target_bounds_;

  // Start and end indices of the tab.
  int from_index_;
  int to_index_;

  DISALLOW_COPY_AND_ASSIGN(MiniMoveAnimation);
};

////////////////////////////////////////////////////////////////////////////////
// TabStripGtk, public:

// static
const int TabStripGtk::mini_to_non_mini_gap_ = 3;

TabStripGtk::TabStripGtk(TabStripModel* model, BrowserWindowGtk* window)
    : current_unselected_width_(TabGtk::GetStandardSize().width()),
      current_selected_width_(TabGtk::GetStandardSize().width()),
      available_width_for_tabs_(-1),
      needs_resize_layout_(false),
      tab_vertical_offset_(0),
      model_(model),
      window_(window),
      theme_service_(GtkThemeService::GetFrom(model->profile())),
      resize_layout_factory_(this),
      added_as_message_loop_observer_(false) {
  theme_service_->InitThemesFor(this);
  registrar_.Add(this, NotificationType::BROWSER_THEME_CHANGED,
                 NotificationService::AllSources());
}

TabStripGtk::~TabStripGtk() {
  model_->RemoveObserver(this);
  tabstrip_.Destroy();

  // Free any remaining tabs.  This is needed to free the very last tab,
  // because it is not animated on close.  This also happens when all of the
  // tabs are closed at once.
  std::vector<TabData>::iterator iterator = tab_data_.begin();
  for (; iterator < tab_data_.end(); iterator++) {
    delete iterator->tab;
  }

  tab_data_.clear();

  // Make sure we unhook ourselves as a message loop observer so that we don't
  // crash in the case where the user closes the last tab in a window.
  RemoveMessageLoopObserver();
}

void TabStripGtk::Init() {
  model_->AddObserver(this);

  tabstrip_.Own(gtk_fixed_new());
  ViewIDUtil::SetID(tabstrip_.get(), VIEW_ID_TAB_STRIP);
  // We want the tab strip to be horizontally shrinkable, so that the Chrome
  // window can be resized freely.
  gtk_widget_set_size_request(tabstrip_.get(), 0,
                              TabGtk::GetMinimumUnselectedSize().height());
  gtk_widget_set_app_paintable(tabstrip_.get(), TRUE);
  gtk_drag_dest_set(tabstrip_.get(), GTK_DEST_DEFAULT_ALL,
                    NULL, 0,
                    static_cast<GdkDragAction>(
                        GDK_ACTION_COPY | GDK_ACTION_MOVE | GDK_ACTION_LINK));
  static const int targets[] = { ui::TEXT_URI_LIST,
                                 ui::NETSCAPE_URL,
                                 ui::TEXT_PLAIN,
                                 -1 };
  ui::SetDestTargetList(tabstrip_.get(), targets);

  g_signal_connect(tabstrip_.get(), "expose-event",
                   G_CALLBACK(OnExposeThunk), this);
  g_signal_connect(tabstrip_.get(), "size-allocate",
                   G_CALLBACK(OnSizeAllocateThunk), this);
  g_signal_connect(tabstrip_.get(), "drag-motion",
                   G_CALLBACK(OnDragMotionThunk), this);
  g_signal_connect(tabstrip_.get(), "drag-drop",
                   G_CALLBACK(OnDragDropThunk), this);
  g_signal_connect(tabstrip_.get(), "drag-leave",
                   G_CALLBACK(OnDragLeaveThunk), this);
  g_signal_connect(tabstrip_.get(), "drag-data-received",
                   G_CALLBACK(OnDragDataReceivedThunk), this);

  newtab_button_.reset(MakeNewTabButton());

  gtk_widget_show_all(tabstrip_.get());

  bounds_ = GetInitialWidgetBounds(tabstrip_.get());

  if (drop_indicator_width == 0) {
    // Direction doesn't matter, both images are the same size.
    GdkPixbuf* drop_image = GetDropArrowImage(true);
    drop_indicator_width = gdk_pixbuf_get_width(drop_image);
    drop_indicator_height = gdk_pixbuf_get_height(drop_image);
  }

  ViewIDUtil::SetDelegateForWidget(widget(), this);
}

void TabStripGtk::Show() {
  gtk_widget_show(tabstrip_.get());
}

void TabStripGtk::Hide() {
  gtk_widget_hide(tabstrip_.get());
}

bool TabStripGtk::IsActiveDropTarget() const {
  for (int i = 0; i < GetTabCount(); ++i) {
    TabGtk* tab = GetTabAt(i);
    if (tab->dragging())
      return true;
  }
  return false;
}

void TabStripGtk::Layout() {
  // Called from:
  // - window resize
  // - animation completion
  StopAnimation();

  GenerateIdealBounds();
  int tab_count = GetTabCount();
  int tab_right = 0;
  for (int i = 0; i < tab_count; ++i) {
    const gfx::Rect& bounds = tab_data_.at(i).ideal_bounds;
    TabGtk* tab = GetTabAt(i);
    tab->set_animating_mini_change(false);
    tab->set_vertical_offset(tab_vertical_offset_);
    SetTabBounds(tab, bounds);
    tab_right = bounds.right();
    tab_right += GetTabHOffset(i + 1);
  }

  LayoutNewTabButton(static_cast<double>(tab_right), current_unselected_width_);
}

void TabStripGtk::SchedulePaint() {
  gtk_widget_queue_draw(tabstrip_.get());
}

void TabStripGtk::SetBounds(const gfx::Rect& bounds) {
  bounds_ = bounds;
}

void TabStripGtk::UpdateLoadingAnimations() {
  for (int i = 0, index = 0; i < GetTabCount(); ++i, ++index) {
    TabGtk* current_tab = GetTabAt(i);
    if (current_tab->closing()) {
      --index;
    } else {
      TabRendererGtk::AnimationState state;
      TabContentsWrapper* contents = model_->GetTabContentsAt(index);
      if (!contents || !contents->tab_contents()->is_loading()) {
        state = TabGtk::ANIMATION_NONE;
      } else if (contents->tab_contents()->waiting_for_response()) {
        state = TabGtk::ANIMATION_WAITING;
      } else {
        state = TabGtk::ANIMATION_LOADING;
      }
      if (current_tab->ValidateLoadingAnimation(state)) {
        // Queue the tab's icon area to be repainted.
        gfx::Rect favicon_bounds = current_tab->favicon_bounds();
        gtk_widget_queue_draw_area(tabstrip_.get(),
            favicon_bounds.x() + current_tab->x(),
            favicon_bounds.y() + current_tab->y(),
            favicon_bounds.width(),
            favicon_bounds.height());
      }
    }
  }
}

bool TabStripGtk::IsCompatibleWith(TabStripGtk* other) {
  return model_->profile() == other->model()->profile();
}

bool TabStripGtk::IsAnimating() const {
  return active_animation_.get() != NULL;
}

void TabStripGtk::DestroyDragController() {
  drag_controller_.reset();
}

void TabStripGtk::DestroyDraggedSourceTab(TabGtk* tab) {
  // We could be running an animation that references this Tab.
  StopAnimation();

  // Make sure we leave the tab_data_ vector in a consistent state, otherwise
  // we'll be pointing to tabs that have been deleted and removed from the
  // child view list.
  std::vector<TabData>::iterator it = tab_data_.begin();
  for (; it != tab_data_.end(); ++it) {
    if (it->tab == tab) {
      if (!model_->closing_all())
        NOTREACHED() << "Leaving in an inconsistent state!";
      tab_data_.erase(it);
      break;
    }
  }

  gtk_container_remove(GTK_CONTAINER(tabstrip_.get()), tab->widget());
  // If we delete the dragged source tab here, the DestroyDragWidget posted
  // task will be run after the tab is deleted, leading to a crash.
  MessageLoop::current()->DeleteSoon(FROM_HERE, tab);

  // Force a layout here, because if we've just quickly drag detached a Tab,
  // the stopping of the active animation above may have left the TabStrip in a
  // bad (visual) state.
  Layout();
}

gfx::Rect TabStripGtk::GetIdealBounds(int index) {
  DCHECK(index >= 0 && index < GetTabCount());
  return tab_data_.at(index).ideal_bounds;
}

void TabStripGtk::SetVerticalOffset(int offset) {
  tab_vertical_offset_ = offset;
  Layout();
}

gfx::Point TabStripGtk::GetTabStripOriginForWidget(GtkWidget* target) {
  int x, y;
  if (!gtk_widget_translate_coordinates(widget(), target,
      -widget()->allocation.x, 0, &x, &y)) {
    // If the tab strip isn't showing, give the coordinates relative to the
    // toplevel instead.
    if (!gtk_widget_translate_coordinates(
        gtk_widget_get_toplevel(widget()), target, 0, 0, &x, &y)) {
      NOTREACHED();
    }
  }
  if (GTK_WIDGET_NO_WINDOW(target)) {
    x += target->allocation.x;
    y += target->allocation.y;
  }
  return gfx::Point(x, y);
}

////////////////////////////////////////////////////////////////////////////////
// ViewIDUtil::Delegate implementation

GtkWidget* TabStripGtk::GetWidgetForViewID(ViewID view_id) {
  if (GetTabCount() > 0) {
    if (view_id == VIEW_ID_TAB_LAST) {
      return GetTabAt(GetTabCount() - 1)->widget();
    } else if ((view_id >= VIEW_ID_TAB_0) && (view_id < VIEW_ID_TAB_LAST)) {
      int index = view_id - VIEW_ID_TAB_0;
      if (index >= 0 && index < GetTabCount()) {
        return GetTabAt(index)->widget();
      } else {
        return NULL;
      }
    }
  }

  return NULL;
}

////////////////////////////////////////////////////////////////////////////////
// TabStripGtk, TabStripModelObserver implementation:

void TabStripGtk::TabInsertedAt(TabContentsWrapper* contents,
                                int index,
                                bool foreground) {
  DCHECK(contents);
  DCHECK(index == TabStripModel::kNoTab || model_->ContainsIndex(index));

  StopAnimation();

  bool contains_tab = false;
  TabGtk* tab = NULL;
  // First see if this Tab is one that was dragged out of this TabStrip and is
  // now being dragged back in. In this case, the DraggedTabController actually
  // has the Tab already constructed and we can just insert it into our list
  // again.
  if (IsDragSessionActive()) {
    tab = drag_controller_->GetDragSourceTabForContents(
        contents->tab_contents());
    if (tab) {
      // If the Tab was detached, it would have been animated closed but not
      // removed, so we need to reset this property.
      tab->set_closing(false);
      tab->ValidateLoadingAnimation(TabRendererGtk::ANIMATION_NONE);
      tab->SetVisible(true);
    }

    // See if we're already in the list. We don't want to add ourselves twice.
    std::vector<TabData>::const_iterator iter = tab_data_.begin();
    for (; iter != tab_data_.end() && !contains_tab; ++iter) {
      if (iter->tab == tab)
        contains_tab = true;
    }
  }

  if (!tab)
    tab = new TabGtk(this);

  // Only insert if we're not already in the list.
  if (!contains_tab) {
    TabData d = { tab, gfx::Rect() };
    tab_data_.insert(tab_data_.begin() + index, d);
    tab->UpdateData(contents->tab_contents(), model_->IsAppTab(index), false);
  }
  tab->set_mini(model_->IsMiniTab(index));
  tab->set_app(model_->IsAppTab(index));
  tab->SetBlocked(model_->IsTabBlocked(index));

  if (gtk_widget_get_parent(tab->widget()) != tabstrip_.get())
    gtk_fixed_put(GTK_FIXED(tabstrip_.get()), tab->widget(), 0, 0);

  // Don't animate the first tab; it looks weird.
  if (GetTabCount() > 1) {
    StartInsertTabAnimation(index);
    // We added the tab at 0x0, we need to force an animation step otherwise
    // if GTK paints before the animation event the tab is painted at 0x0
    // which is most likely not where it should be positioned.
    active_animation_->AnimationProgressed(NULL);
  } else {
    Layout();
  }
}

void TabStripGtk::TabDetachedAt(TabContentsWrapper* contents, int index) {
  GenerateIdealBounds();
  StartRemoveTabAnimation(index, contents->tab_contents());
  // Have to do this _after_ calling StartRemoveTabAnimation, so that any
  // previous remove is completed fully and index is valid in sync with the
  // model index.
  GetTabAt(index)->set_closing(true);
}

void TabStripGtk::TabSelectedAt(TabContentsWrapper* old_contents,
                                TabContentsWrapper* new_contents,
                                int index,
                                bool user_gesture) {
  DCHECK(index >= 0 && index < static_cast<int>(GetTabCount()));

  // We have "tiny tabs" if the tabs are so tiny that the unselected ones are
  // a different size to the selected ones.
  bool tiny_tabs = current_unselected_width_ != current_selected_width_;
  if (!IsAnimating() && (!needs_resize_layout_ || tiny_tabs))
    Layout();

  GetTabAt(index)->SchedulePaint();

  int old_index = model_->GetIndexOfTabContents(old_contents);
  if (old_index >= 0) {
    GetTabAt(old_index)->SchedulePaint();
    GetTabAt(old_index)->StopMiniTabTitleAnimation();
  }
}

void TabStripGtk::TabMoved(TabContentsWrapper* contents,
                           int from_index,
                           int to_index) {
  gfx::Rect start_bounds = GetIdealBounds(from_index);
  TabGtk* tab = GetTabAt(from_index);
  tab_data_.erase(tab_data_.begin() + from_index);
  TabData data = {tab, gfx::Rect()};
  tab->set_mini(model_->IsMiniTab(to_index));
  tab->SetBlocked(model_->IsTabBlocked(to_index));
  tab_data_.insert(tab_data_.begin() + to_index, data);
  GenerateIdealBounds();
  StartMoveTabAnimation(from_index, to_index);
}

void TabStripGtk::TabChangedAt(TabContentsWrapper* contents, int index,
                               TabChangeType change_type) {
  // Index is in terms of the model. Need to make sure we adjust that index in
  // case we have an animation going.
  TabGtk* tab = GetTabAtAdjustForAnimation(index);
  if (change_type == TITLE_NOT_LOADING) {
    if (tab->mini() && !tab->IsSelected())
      tab->StartMiniTabTitleAnimation();
    // We'll receive another notification of the change asynchronously.
    return;
  }
  tab->UpdateData(contents->tab_contents(),
                  model_->IsAppTab(index),
                  change_type == LOADING_ONLY);
  tab->UpdateFromModel();
}

void TabStripGtk::TabReplacedAt(TabStripModel* tab_strip_model,
                                TabContentsWrapper* old_contents,
                                TabContentsWrapper* new_contents,
                                int index) {
  TabChangedAt(new_contents, index, ALL);
}

void TabStripGtk::TabMiniStateChanged(TabContentsWrapper* contents, int index) {
  // Don't do anything if we've already picked up the change from TabMoved.
  if (GetTabAt(index)->mini() == model_->IsMiniTab(index))
    return;

  GetTabAt(index)->set_mini(model_->IsMiniTab(index));
  // Don't animate if the window isn't visible yet. The window won't be visible
  // when dragging a mini-tab to a new window.
  if (window_ && window_->window() &&
      GTK_WIDGET_VISIBLE(GTK_WIDGET(window_->window()))) {
    StartMiniTabAnimation(index);
  } else {
    Layout();
  }
}

void TabStripGtk::TabBlockedStateChanged(TabContentsWrapper* contents,
                                         int index) {
  GetTabAt(index)->SetBlocked(model_->IsTabBlocked(index));
}

////////////////////////////////////////////////////////////////////////////////
// TabStripGtk, TabGtk::TabDelegate implementation:

bool TabStripGtk::IsTabSelected(const TabGtk* tab) const {
  if (tab->closing())
    return false;

  return GetIndexOfTab(tab) == model_->active_index();
}

bool TabStripGtk::IsTabDetached(const TabGtk* tab) const {
  if (drag_controller_.get())
    return drag_controller_->IsTabDetached(tab);
  return false;
}

void TabStripGtk::GetCurrentTabWidths(double* unselected_width,
                                      double* selected_width) const {
  *unselected_width = current_unselected_width_;
  *selected_width = current_selected_width_;
}

bool TabStripGtk::IsTabPinned(const TabGtk* tab) const {
  if (tab->closing())
    return false;

  return model_->IsTabPinned(GetIndexOfTab(tab));
}

void TabStripGtk::SelectTab(TabGtk* tab) {
  int index = GetIndexOfTab(tab);
  if (model_->ContainsIndex(index))
    model_->ActivateTabAt(index, true);
}

void TabStripGtk::CloseTab(TabGtk* tab) {
  int tab_index = GetIndexOfTab(tab);
  if (model_->ContainsIndex(tab_index)) {
    TabGtk* last_tab = GetTabAt(GetTabCount() - 1);
    // Limit the width available to the TabStrip for laying out Tabs, so that
    // Tabs are not resized until a later time (when the mouse pointer leaves
    // the TabStrip).
    available_width_for_tabs_ = GetAvailableWidthForTabs(last_tab);
    needs_resize_layout_ = true;
    // We hook into the message loop in order to receive mouse move events when
    // the mouse is outside of the tabstrip.  We unhook once the resize layout
    // animation is started.
    AddMessageLoopObserver();
    model_->CloseTabContentsAt(tab_index,
                               TabStripModel::CLOSE_USER_GESTURE |
                               TabStripModel::CLOSE_CREATE_HISTORICAL_TAB);
  }
}

bool TabStripGtk::IsCommandEnabledForTab(
    TabStripModel::ContextMenuCommand command_id, const TabGtk* tab) const {
  int index = GetIndexOfTab(tab);
  if (model_->ContainsIndex(index))
    return model_->IsContextMenuCommandEnabled(index, command_id);
  return false;
}

void TabStripGtk::ExecuteCommandForTab(
    TabStripModel::ContextMenuCommand command_id, TabGtk* tab) {
  int index = GetIndexOfTab(tab);
  if (model_->ContainsIndex(index))
    model_->ExecuteContextMenuCommand(index, command_id);
}

void TabStripGtk::StartHighlightTabsForCommand(
    TabStripModel::ContextMenuCommand command_id, TabGtk* tab) {
  if (command_id == TabStripModel::CommandCloseOtherTabs ||
      command_id == TabStripModel::CommandCloseTabsToRight) {
    NOTIMPLEMENTED();
  }
}

void TabStripGtk::StopHighlightTabsForCommand(
    TabStripModel::ContextMenuCommand command_id, TabGtk* tab) {
  if (command_id == TabStripModel::CommandCloseTabsToRight ||
      command_id == TabStripModel::CommandCloseOtherTabs) {
    // Just tell all Tabs to stop pulsing - it's safe.
    StopAllHighlighting();
  }
}

void TabStripGtk::StopAllHighlighting() {
  // TODO(jhawkins): Hook up animations.
  NOTIMPLEMENTED();
}

void TabStripGtk::MaybeStartDrag(TabGtk* tab, const gfx::Point& point) {
  // Don't accidentally start any drag operations during animations if the
  // mouse is down.
  if (IsAnimating() || tab->closing() || !HasAvailableDragActions())
    return;

  drag_controller_.reset(new DraggedTabControllerGtk(tab, this));
  drag_controller_->CaptureDragInfo(point);
}

void TabStripGtk::ContinueDrag(GdkDragContext* context) {
  // We can get called even if |MaybeStartDrag| wasn't called in the event of
  // a TabStrip animation when the mouse button is down. In this case we should
  // _not_ continue the drag because it can lead to weird bugs.
  if (drag_controller_.get())
    drag_controller_->Drag();
}

bool TabStripGtk::EndDrag(bool canceled) {
  return drag_controller_.get() ? drag_controller_->EndDrag(canceled) : false;
}

bool TabStripGtk::HasAvailableDragActions() const {
  return model_->delegate()->GetDragActions() != 0;
}

ui::ThemeProvider* TabStripGtk::GetThemeProvider() {
  return theme_service_;
}

///////////////////////////////////////////////////////////////////////////////
// TabStripGtk, MessageLoop::Observer implementation:

void TabStripGtk::WillProcessEvent(GdkEvent* event) {
  // Nothing to do.
}

void TabStripGtk::DidProcessEvent(GdkEvent* event) {
  switch (event->type) {
    case GDK_MOTION_NOTIFY:
    case GDK_LEAVE_NOTIFY:
      HandleGlobalMouseMoveEvent();
      break;
    default:
      break;
  }
}

///////////////////////////////////////////////////////////////////////////////
// TabStripGtk, NotificationObserver implementation:

void TabStripGtk::Observe(NotificationType type,
                          const NotificationSource& source,
                          const NotificationDetails& details) {
  if (type == NotificationType::BROWSER_THEME_CHANGED) {
    TabRendererGtk::SetSelectedTitleColor(theme_service_->GetColor(
        ThemeService::COLOR_TAB_TEXT));
    TabRendererGtk::SetUnselectedTitleColor(theme_service_->GetColor(
        ThemeService::COLOR_BACKGROUND_TAB_TEXT));
  }
}

////////////////////////////////////////////////////////////////////////////////
// TabStripGtk, private:

int TabStripGtk::GetTabCount() const {
  return static_cast<int>(tab_data_.size());
}

int TabStripGtk::GetMiniTabCount() const {
  int mini_count = 0;
  for (size_t i = 0; i < tab_data_.size(); ++i) {
    if (tab_data_[i].tab->mini())
      mini_count++;
    else
      return mini_count;
  }
  return mini_count;
}

int TabStripGtk::GetAvailableWidthForTabs(TabGtk* last_tab) const {
  if (!base::i18n::IsRTL())
    return last_tab->x() - bounds_.x() + last_tab->width();
  else
    return bounds_.width() - last_tab->x();
}

int TabStripGtk::GetIndexOfTab(const TabGtk* tab) const {
  for (int i = 0, index = 0; i < GetTabCount(); ++i, ++index) {
    TabGtk* current_tab = GetTabAt(i);
    if (current_tab->closing()) {
      --index;
    } else if (current_tab == tab) {
      return index;
    }
  }
  return -1;
}

TabGtk* TabStripGtk::GetTabAt(int index) const {
  DCHECK_GE(index, 0);
  DCHECK_LT(index, GetTabCount());
  return tab_data_.at(index).tab;
}

TabGtk* TabStripGtk::GetTabAtAdjustForAnimation(int index) const {
  if (active_animation_.get() &&
      active_animation_->type() == TabAnimation::REMOVE &&
      index >=
      static_cast<RemoveTabAnimation*>(active_animation_.get())->index()) {
    index++;
  }
  return GetTabAt(index);
}

void TabStripGtk::RemoveTabAt(int index) {
  TabGtk* removed = tab_data_.at(index).tab;

  // Remove the Tab from the TabStrip's list.
  tab_data_.erase(tab_data_.begin() + index);

  if (!IsDragSessionActive() || !drag_controller_->IsDragSourceTab(removed)) {
    gtk_container_remove(GTK_CONTAINER(tabstrip_.get()), removed->widget());
    delete removed;
  }
}

void TabStripGtk::HandleGlobalMouseMoveEvent() {
  if (!IsCursorInTabStripZone()) {
    // Mouse moved outside the tab slop zone, start a timer to do a resize
    // layout after a short while...
    if (resize_layout_factory_.empty()) {
      MessageLoop::current()->PostDelayedTask(FROM_HERE,
          resize_layout_factory_.NewRunnableMethod(
              &TabStripGtk::ResizeLayoutTabs),
          kResizeTabsTimeMs);
    }
  } else {
    // Mouse moved quickly out of the tab strip and then into it again, so
    // cancel the timer so that the strip doesn't move when the mouse moves
    // back over it.
    resize_layout_factory_.RevokeAll();
  }
}

void TabStripGtk::GenerateIdealBounds() {
  int tab_count = GetTabCount();
  double unselected, selected;
  GetDesiredTabWidths(tab_count, GetMiniTabCount(), &unselected, &selected);

  current_unselected_width_ = unselected;
  current_selected_width_ = selected;

  // NOTE: This currently assumes a tab's height doesn't differ based on
  // selected state or the number of tabs in the strip!
  int tab_height = TabGtk::GetStandardSize().height();
  double tab_x = tab_start_x();
  for (int i = 0; i < tab_count; ++i) {
    TabGtk* tab = GetTabAt(i);
    double tab_width = unselected;
    if (tab->mini())
      tab_width = TabGtk::GetMiniWidth();
    else if (tab->IsSelected())
      tab_width = selected;
    double end_of_tab = tab_x + tab_width;
    int rounded_tab_x = Round(tab_x);
    gfx::Rect state(rounded_tab_x, 0, Round(end_of_tab) - rounded_tab_x,
                    tab_height);
    tab_data_.at(i).ideal_bounds = state;
    tab_x = end_of_tab + GetTabHOffset(i + 1);
  }
}

void TabStripGtk::LayoutNewTabButton(double last_tab_right,
                                     double unselected_width) {
  gfx::Rect bounds(0, kNewTabButtonVOffset,
                   newtab_button_->width(), newtab_button_->height());
  int delta = abs(Round(unselected_width) - TabGtk::GetStandardSize().width());
  if (delta > 1 && !needs_resize_layout_) {
    // We're shrinking tabs, so we need to anchor the New Tab button to the
    // right edge of the TabStrip's bounds, rather than the right edge of the
    // right-most Tab, otherwise it'll bounce when animating.
    bounds.set_x(bounds_.width() - newtab_button_->width());
  } else {
    bounds.set_x(Round(last_tab_right - kTabHOffset) + kNewTabButtonHOffset);
  }
  bounds.set_x(gtk_util::MirroredLeftPointForRect(tabstrip_.get(), bounds));

  gtk_fixed_move(GTK_FIXED(tabstrip_.get()), newtab_button_->widget(),
                 bounds.x(), bounds.y());
}

void TabStripGtk::GetDesiredTabWidths(int tab_count,
                                      int mini_tab_count,
                                      double* unselected_width,
                                      double* selected_width) const {
  DCHECK(tab_count >= 0 && mini_tab_count >= 0 && mini_tab_count <= tab_count);
  const double min_unselected_width =
      TabGtk::GetMinimumUnselectedSize().width();
  const double min_selected_width =
      TabGtk::GetMinimumSelectedSize().width();

  *unselected_width = min_unselected_width;
  *selected_width = min_selected_width;

  if (tab_count == 0) {
    // Return immediately to avoid divide-by-zero below.
    return;
  }

  // Determine how much space we can actually allocate to tabs.
  int available_width = tabstrip_->allocation.width;
  if (available_width_for_tabs_ < 0) {
    available_width = bounds_.width();
    available_width -=
        (kNewTabButtonHOffset + newtab_button_->width());
  } else {
    // Interesting corner case: if |available_width_for_tabs_| > the result
    // of the calculation in the conditional arm above, the strip is in
    // overflow.  We can either use the specified width or the true available
    // width here; the first preserves the consistent "leave the last tab under
    // the user's mouse so they can close many tabs" behavior at the cost of
    // prolonging the glitchy appearance of the overflow state, while the second
    // gets us out of overflow as soon as possible but forces the user to move
    // their mouse for a few tabs' worth of closing.  We choose visual
    // imperfection over behavioral imperfection and select the first option.
    available_width = available_width_for_tabs_;
  }

  if (mini_tab_count > 0) {
    available_width -= mini_tab_count * (TabGtk::GetMiniWidth() + kTabHOffset);
    tab_count -= mini_tab_count;
    if (tab_count == 0) {
      *selected_width = *unselected_width = TabGtk::GetStandardSize().width();
      return;
    }
    // Account for gap between the last mini-tab and first normal tab.
    available_width -= mini_to_non_mini_gap_;
  }

  // Calculate the desired tab widths by dividing the available space into equal
  // portions.  Don't let tabs get larger than the "standard width" or smaller
  // than the minimum width for each type, respectively.
  const int total_offset = kTabHOffset * (tab_count - 1);
  const double desired_tab_width = std::min(
      (static_cast<double>(available_width - total_offset) /
       static_cast<double>(tab_count)),
      static_cast<double>(TabGtk::GetStandardSize().width()));

  *unselected_width = std::max(desired_tab_width, min_unselected_width);
  *selected_width = std::max(desired_tab_width, min_selected_width);

  // When there are multiple tabs, we'll have one selected and some unselected
  // tabs.  If the desired width was between the minimum sizes of these types,
  // try to shrink the tabs with the smaller minimum.  For example, if we have
  // a strip of width 10 with 4 tabs, the desired width per tab will be 2.5.  If
  // selected tabs have a minimum width of 4 and unselected tabs have a minimum
  // width of 1, the above code would set *unselected_width = 2.5,
  // *selected_width = 4, which results in a total width of 11.5.  Instead, we
  // want to set *unselected_width = 2, *selected_width = 4, for a total width
  // of 10.
  if (tab_count > 1) {
    if ((min_unselected_width < min_selected_width) &&
        (desired_tab_width < min_selected_width)) {
      double calc_width =
          static_cast<double>(
              available_width - total_offset - min_selected_width) /
          static_cast<double>(tab_count - 1);
      *unselected_width = std::max(calc_width, min_unselected_width);
    } else if ((min_unselected_width > min_selected_width) &&
               (desired_tab_width < min_unselected_width)) {
      *selected_width = std::max(available_width - total_offset -
          (min_unselected_width * (tab_count - 1)), min_selected_width);
    }
  }
}

int TabStripGtk::GetTabHOffset(int tab_index) {
  if (tab_index < GetTabCount() && GetTabAt(tab_index - 1)->mini() &&
      !GetTabAt(tab_index)->mini()) {
    return mini_to_non_mini_gap_ + kTabHOffset;
  }
  return kTabHOffset;
}

int TabStripGtk::tab_start_x() const {
  return 0;
}

bool TabStripGtk::ResizeLayoutTabs() {
  resize_layout_factory_.RevokeAll();

  // It is critically important that this is unhooked here, otherwise we will
  // keep spying on messages forever.
  RemoveMessageLoopObserver();

  available_width_for_tabs_ = -1;
  int mini_tab_count = GetMiniTabCount();
  if (mini_tab_count == GetTabCount()) {
    // Only mini tabs, we know the tab widths won't have changed (all mini-tabs
    // have the same width), so there is nothing to do.
    return false;
  }
  TabGtk* first_tab = GetTabAt(mini_tab_count);
  double unselected, selected;
  GetDesiredTabWidths(GetTabCount(), mini_tab_count, &unselected, &selected);
  int w = Round(first_tab->IsSelected() ? selected : unselected);

  // We only want to run the animation if we're not already at the desired
  // size.
  if (abs(first_tab->width() - w) > 1) {
    StartResizeLayoutAnimation();
    return true;
  }

  return false;
}

bool TabStripGtk::IsCursorInTabStripZone() const {
  gfx::Point tabstrip_topleft;
  gtk_util::ConvertWidgetPointToScreen(tabstrip_.get(), &tabstrip_topleft);

  gfx::Rect bds = bounds();
  bds.set_origin(tabstrip_topleft);
  bds.set_height(bds.height() + kTabStripAnimationVSlop);

  GdkScreen* screen = gdk_screen_get_default();
  GdkDisplay* display = gdk_screen_get_display(screen);
  gint x, y;
  gdk_display_get_pointer(display, NULL, &x, &y, NULL);
  gfx::Point cursor_point(x, y);

  return bds.Contains(cursor_point);
}

void TabStripGtk::AddMessageLoopObserver() {
  if (!added_as_message_loop_observer_) {
    MessageLoopForUI::current()->AddObserver(this);
    added_as_message_loop_observer_ = true;
  }
}

void TabStripGtk::RemoveMessageLoopObserver() {
  if (added_as_message_loop_observer_) {
    MessageLoopForUI::current()->RemoveObserver(this);
    added_as_message_loop_observer_ = false;
  }
}

gfx::Rect TabStripGtk::GetDropBounds(int drop_index,
                                     bool drop_before,
                                     bool* is_beneath) {
  DCHECK_NE(drop_index, -1);
  int center_x;
  if (drop_index < GetTabCount()) {
    TabGtk* tab = GetTabAt(drop_index);
    gfx::Rect bounds = tab->GetNonMirroredBounds(tabstrip_.get());
    // TODO(sky): update these for pinned tabs.
    if (drop_before)
      center_x = bounds.x() - (kTabHOffset / 2);
    else
      center_x = bounds.x() + (bounds.width() / 2);
  } else {
    TabGtk* last_tab = GetTabAt(drop_index - 1);
    gfx::Rect bounds = last_tab->GetNonMirroredBounds(tabstrip_.get());
    center_x = bounds.x() + bounds.width() + (kTabHOffset / 2);
  }

  center_x = gtk_util::MirroredXCoordinate(tabstrip_.get(), center_x);

  // Determine the screen bounds.
  gfx::Point drop_loc(center_x - drop_indicator_width / 2,
                      -drop_indicator_height);
  gtk_util::ConvertWidgetPointToScreen(tabstrip_.get(), &drop_loc);
  gfx::Rect drop_bounds(drop_loc.x(), drop_loc.y(), drop_indicator_width,
                        drop_indicator_height);

  // TODO(jhawkins): We always display the arrow underneath the tab because we
  // don't have custom frame support yet.
  *is_beneath = true;
  if (*is_beneath)
    drop_bounds.Offset(0, drop_bounds.height() + bounds().height());

  return drop_bounds;
}

void TabStripGtk::UpdateDropIndex(GdkDragContext* context, gint x, gint y) {
  // If the UI layout is right-to-left, we need to mirror the mouse
  // coordinates since we calculate the drop index based on the
  // original (and therefore non-mirrored) positions of the tabs.
  x = gtk_util::MirroredXCoordinate(tabstrip_.get(), x);
  // We don't allow replacing the urls of mini-tabs.
  for (int i = GetMiniTabCount(); i < GetTabCount(); ++i) {
    TabGtk* tab = GetTabAt(i);
    gfx::Rect bounds = tab->GetNonMirroredBounds(tabstrip_.get());
    const int tab_max_x = bounds.x() + bounds.width();
    const int hot_width = bounds.width() / 3;
    if (x < tab_max_x) {
      if (x < bounds.x() + hot_width)
        SetDropIndex(i, true);
      else if (x >= tab_max_x - hot_width)
        SetDropIndex(i + 1, true);
      else
        SetDropIndex(i, false);
      return;
    }
  }

  // The drop isn't over a tab, add it to the end.
  SetDropIndex(GetTabCount(), true);
}

void TabStripGtk::SetDropIndex(int index, bool drop_before) {
  bool is_beneath;
  gfx::Rect drop_bounds = GetDropBounds(index, drop_before, &is_beneath);

  if (!drop_info_.get()) {
    drop_info_.reset(new DropInfo(index, drop_before, !is_beneath));
  } else {
    if (!GTK_IS_WIDGET(drop_info_->container)) {
      drop_info_->CreateContainer();
    } else if (drop_info_->drop_index == index &&
               drop_info_->drop_before == drop_before) {
      return;
    }

    drop_info_->drop_index = index;
    drop_info_->drop_before = drop_before;
    if (is_beneath == drop_info_->point_down) {
      drop_info_->point_down = !is_beneath;
      drop_info_->drop_arrow= GetDropArrowImage(drop_info_->point_down);
    }
  }

  gtk_window_move(GTK_WINDOW(drop_info_->container),
                  drop_bounds.x(), drop_bounds.y());
  gtk_window_resize(GTK_WINDOW(drop_info_->container),
                    drop_bounds.width(), drop_bounds.height());
}

bool TabStripGtk::CompleteDrop(guchar* data, bool is_plain_text) {
  if (!drop_info_.get())
    return false;

  const int drop_index = drop_info_->drop_index;
  const bool drop_before = drop_info_->drop_before;

  // Destroy the drop indicator.
  drop_info_.reset();

  GURL url;
  if (is_plain_text) {
    AutocompleteMatch match;
    model_->profile()->GetAutocompleteClassifier()->Classify(
        UTF8ToUTF16(reinterpret_cast<char*>(data)), string16(), false,
        &match, NULL);
    url = match.destination_url;
  } else {
    std::string url_string(reinterpret_cast<char*>(data));
    url = GURL(url_string.substr(0, url_string.find_first_of('\n')));
  }
  if (!url.is_valid())
    return false;

  browser::NavigateParams params(window()->browser(), url,
                                 PageTransition::LINK);
  params.tabstrip_index = drop_index;

  if (drop_before) {
    params.disposition = NEW_FOREGROUND_TAB;
  } else {
    params.disposition = CURRENT_TAB;
    params.source_contents = model_->GetTabContentsAt(drop_index);
  }

  browser::Navigate(&params);

  return true;
}

// static
GdkPixbuf* TabStripGtk::GetDropArrowImage(bool is_down) {
  return ResourceBundle::GetSharedInstance().GetPixbufNamed(
      is_down ? IDR_TAB_DROP_DOWN : IDR_TAB_DROP_UP);
}

// TabStripGtk::DropInfo -------------------------------------------------------

TabStripGtk::DropInfo::DropInfo(int drop_index, bool drop_before,
                                bool point_down)
    : drop_index(drop_index),
      drop_before(drop_before),
      point_down(point_down) {
  CreateContainer();
  drop_arrow = GetDropArrowImage(point_down);
}

TabStripGtk::DropInfo::~DropInfo() {
  DestroyContainer();
}

gboolean TabStripGtk::DropInfo::OnExposeEvent(GtkWidget* widget,
                                              GdkEventExpose* event) {
  if (gtk_util::IsScreenComposited()) {
    SetContainerTransparency();
  } else {
    SetContainerShapeMask();
  }

  gdk_pixbuf_render_to_drawable(drop_arrow,
                                container->window,
                                0, 0, 0,
                                0, 0,
                                drop_indicator_width,
                                drop_indicator_height,
                                GDK_RGB_DITHER_NONE, 0, 0);

  return FALSE;
}

// Sets the color map of the container window to allow the window to be
// transparent.
void TabStripGtk::DropInfo::SetContainerColorMap() {
  GdkScreen* screen = gtk_widget_get_screen(container);
  GdkColormap* colormap = gdk_screen_get_rgba_colormap(screen);

  // If rgba is not available, use rgb instead.
  if (!colormap)
    colormap = gdk_screen_get_rgb_colormap(screen);

  gtk_widget_set_colormap(container, colormap);
}

// Sets full transparency for the container window.  This is used if
// compositing is available for the screen.
void TabStripGtk::DropInfo::SetContainerTransparency() {
  cairo_t* cairo_context = gdk_cairo_create(container->window);
  if (!cairo_context)
      return;

  // Make the background of the dragged tab window fully transparent.  All of
  // the content of the window (child widgets) will be completely opaque.

  cairo_scale(cairo_context, static_cast<double>(drop_indicator_width),
              static_cast<double>(drop_indicator_height));
  cairo_set_source_rgba(cairo_context, 1.0f, 1.0f, 1.0f, 0.0f);
  cairo_set_operator(cairo_context, CAIRO_OPERATOR_SOURCE);
  cairo_paint(cairo_context);
  cairo_destroy(cairo_context);
}

// Sets the shape mask for the container window to emulate a transparent
// container window.  This is used if compositing is not available for the
// screen.
void TabStripGtk::DropInfo::SetContainerShapeMask() {
  // Create a 1bpp bitmap the size of |container|.
  GdkPixmap* pixmap = gdk_pixmap_new(NULL,
                                     drop_indicator_width,
                                     drop_indicator_height, 1);
  cairo_t* cairo_context = gdk_cairo_create(GDK_DRAWABLE(pixmap));

  // Set the transparency.
  cairo_set_source_rgba(cairo_context, 1, 1, 1, 0);

  // Blit the rendered bitmap into a pixmap.  Any pixel set in the pixmap will
  // be opaque in the container window.
  cairo_set_operator(cairo_context, CAIRO_OPERATOR_SOURCE);
  gdk_cairo_set_source_pixbuf(cairo_context, drop_arrow, 0, 0);
  cairo_paint(cairo_context);
  cairo_destroy(cairo_context);

  // Set the shape mask.
  gdk_window_shape_combine_mask(container->window, pixmap, 0, 0);
  g_object_unref(pixmap);
}

void TabStripGtk::DropInfo::CreateContainer() {
  container = gtk_window_new(GTK_WINDOW_POPUP);
  SetContainerColorMap();
  gtk_widget_set_app_paintable(container, TRUE);
  g_signal_connect(container, "expose-event",
                   G_CALLBACK(OnExposeEventThunk), this);
  gtk_widget_add_events(container, GDK_STRUCTURE_MASK);
  gtk_window_move(GTK_WINDOW(container), 0, 0);
  gtk_window_resize(GTK_WINDOW(container),
                    drop_indicator_width, drop_indicator_height);
  gtk_widget_show_all(container);
}

void TabStripGtk::DropInfo::DestroyContainer() {
  if (GTK_IS_WIDGET(container))
    gtk_widget_destroy(container);
}

void TabStripGtk::StopAnimation() {
  if (active_animation_.get())
    active_animation_->Stop();
}

// Called from:
// - animation tick
void TabStripGtk::AnimationLayout(double unselected_width) {
  int tab_height = TabGtk::GetStandardSize().height();
  double tab_x = tab_start_x();
  for (int i = 0; i < GetTabCount(); ++i) {
    TabAnimation* animation = active_animation_.get();
    if (animation)
      tab_x += animation->GetGapWidth(i);
    double tab_width = TabAnimation::GetCurrentTabWidth(this, animation, i);
    double end_of_tab = tab_x + tab_width;
    int rounded_tab_x = Round(tab_x);
    TabGtk* tab = GetTabAt(i);
    gfx::Rect bounds(rounded_tab_x, 0, Round(end_of_tab) - rounded_tab_x,
                     tab_height);
    SetTabBounds(tab, bounds);
    tab_x = end_of_tab + GetTabHOffset(i + 1);
  }
  LayoutNewTabButton(tab_x, unselected_width);
}

void TabStripGtk::StartInsertTabAnimation(int index) {
  // The TabStrip can now use its entire width to lay out Tabs.
  available_width_for_tabs_ = -1;
  StopAnimation();
  active_animation_.reset(new InsertTabAnimation(this, index));
  active_animation_->Start();
}

void TabStripGtk::StartRemoveTabAnimation(int index, TabContents* contents) {
  if (active_animation_.get()) {
    // Some animations (e.g. MoveTabAnimation) cause there to be a Layout when
    // they're completed (which includes canceled). Since |tab_data_| is now
    // inconsistent with TabStripModel, doing this Layout will crash now, so
    // we ask the MoveTabAnimation to skip its Layout (the state will be
    // corrected by the RemoveTabAnimation we're about to initiate).
    active_animation_->set_layout_on_completion(false);
    active_animation_->Stop();
  }

  active_animation_.reset(new RemoveTabAnimation(this, index, contents));
  active_animation_->Start();
}

void TabStripGtk::StartMoveTabAnimation(int from_index, int to_index) {
  StopAnimation();
  active_animation_.reset(new MoveTabAnimation(this, from_index, to_index));
  active_animation_->Start();
}

void TabStripGtk::StartResizeLayoutAnimation() {
  StopAnimation();
  active_animation_.reset(new ResizeLayoutAnimation(this));
  active_animation_->Start();
}

void TabStripGtk::StartMiniTabAnimation(int index) {
  StopAnimation();
  active_animation_.reset(new MiniTabAnimation(this, index));
  active_animation_->Start();
}

void TabStripGtk::StartMiniMoveTabAnimation(int from_index,
                                            int to_index,
                                            const gfx::Rect& start_bounds) {
  StopAnimation();
  active_animation_.reset(
      new MiniMoveAnimation(this, from_index, to_index, start_bounds));
  active_animation_->Start();
}

void TabStripGtk::FinishAnimation(TabStripGtk::TabAnimation* animation,
                                  bool layout) {
  active_animation_.reset(NULL);

  // Reset the animation state of each tab.
  for (int i = 0, count = GetTabCount(); i < count; ++i)
    GetTabAt(i)->set_animating_mini_change(false);

  if (layout)
    Layout();
}

gboolean TabStripGtk::OnExpose(GtkWidget* widget, GdkEventExpose* event) {
  if (gdk_region_empty(event->region))
    return TRUE;

  // If we're only repainting favicons, optimize the paint path and only draw
  // the favicons.
  GdkRectangle* rects;
  gint num_rects;
  gdk_region_get_rectangles(event->region, &rects, &num_rects);
  qsort(rects, num_rects, sizeof(GdkRectangle), CompareGdkRectangles);
  std::vector<int> tabs_to_repaint;
  if (!IsDragSessionActive() &&
      CanPaintOnlyFavicons(rects, num_rects, &tabs_to_repaint)) {
    PaintOnlyFavicons(event, tabs_to_repaint);
    g_free(rects);
    return TRUE;
  }
  g_free(rects);

  // TODO(jhawkins): Ideally we'd like to only draw what's needed in the damage
  // rect, but the tab widgets overlap each other, and painting on one widget
  // will cause an expose-event to be sent to the widgets underneath.  The
  // underlying widget does not need to be redrawn as we control the order of
  // expose-events.  Currently we hack it to redraw the entire tabstrip.  We
  // could change the damage rect to just contain the tabs + the new tab button.
  event->area.x = 0;
  event->area.y = 0;
  event->area.width = bounds_.width();
  event->area.height = bounds_.height();
  gdk_region_union_with_rect(event->region, &event->area);

  // Paint the New Tab button.
  gtk_container_propagate_expose(GTK_CONTAINER(tabstrip_.get()),
      newtab_button_->widget(), event);

  // Paint the tabs in reverse order, so they stack to the left.
  TabGtk* selected_tab = NULL;
  int tab_count = GetTabCount();
  for (int i = tab_count - 1; i >= 0; --i) {
    TabGtk* tab = GetTabAt(i);
    // We must ask the _Tab's_ model, not ourselves, because in some situations
    // the model will be different to this object, e.g. when a Tab is being
    // removed after its TabContents has been destroyed.
    if (!tab->IsSelected()) {
      gtk_container_propagate_expose(GTK_CONTAINER(tabstrip_.get()),
                                     tab->widget(), event);
    } else {
      selected_tab = tab;
    }
  }

  // Paint the selected tab last, so it overlaps all the others.
  if (selected_tab) {
    gtk_container_propagate_expose(GTK_CONTAINER(tabstrip_.get()),
                                   selected_tab->widget(), event);
  }

  return TRUE;
}

void TabStripGtk::OnSizeAllocate(GtkWidget* widget, GtkAllocation* allocation) {
  gfx::Rect bounds = gfx::Rect(allocation->x, allocation->y,
      allocation->width, allocation->height);

  // Nothing to do if the bounds are the same.  If we don't catch this, we'll
  // get an infinite loop of size-allocate signals.
  if (bounds_ == bounds)
    return;

  SetBounds(bounds);

  // No tabs, nothing to layout.  This happens when a browser window is created
  // and shown before tabs are added (as in a popup window).
  if (GetTabCount() == 0)
    return;

  // When there is only one tab, Layout() so we don't animate it. With more
  // tabs, do ResizeLayoutTabs(). In RTL(), we will also need to manually
  // Layout() when ResizeLayoutTabs() is a no-op.
  if ((GetTabCount() == 1) || (!ResizeLayoutTabs() && base::i18n::IsRTL()))
    Layout();
}

gboolean TabStripGtk::OnDragMotion(GtkWidget* widget, GdkDragContext* context,
                                   gint x, gint y, guint time) {
  UpdateDropIndex(context, x, y);
  return TRUE;
}

gboolean TabStripGtk::OnDragDrop(GtkWidget* widget, GdkDragContext* context,
                                 gint x, gint y, guint time) {
  if (!drop_info_.get())
    return FALSE;

  GdkAtom target = gtk_drag_dest_find_target(widget, context, NULL);
  if (target != GDK_NONE)
    gtk_drag_finish(context, FALSE, FALSE, time);
  else
    gtk_drag_get_data(widget, context, target, time);

  return TRUE;
}

gboolean TabStripGtk::OnDragLeave(GtkWidget* widget, GdkDragContext* context,
                                  guint time) {
  // Destroy the drop indicator.
  drop_info_->DestroyContainer();
  return FALSE;
}

gboolean TabStripGtk::OnDragDataReceived(GtkWidget* widget,
                                         GdkDragContext* context,
                                         gint x, gint y,
                                         GtkSelectionData* data,
                                         guint info, guint time) {
  bool success = false;

  if (info == ui::TEXT_URI_LIST ||
      info == ui::NETSCAPE_URL ||
      info == ui::TEXT_PLAIN) {
    success = CompleteDrop(data->data, info == ui::TEXT_PLAIN);
  }

  gtk_drag_finish(context, success, success, time);
  return TRUE;
}

void TabStripGtk::OnNewTabClicked(GtkWidget* widget) {
  GdkEvent* event = gtk_get_current_event();
  DCHECK_EQ(event->type, GDK_BUTTON_RELEASE);
  int mouse_button = event->button.button;
  gdk_event_free(event);

  switch (mouse_button) {
    case 1:
      model_->delegate()->AddBlankTab(true);
      break;
    case 2: {
      // On middle-click, try to parse the PRIMARY selection as a URL and load
      // it instead of creating a blank page.
      GURL url;
      if (!gtk_util::URLFromPrimarySelection(model_->profile(), &url))
        return;

      Browser* browser = window_->browser();
      DCHECK(browser);
      browser->AddSelectedTabWithURL(url, PageTransition::TYPED);
      break;
    }
    default:
      NOTREACHED() << "Got click on new tab button with unhandled mouse "
                   << "button " << mouse_button;
  }
}

void TabStripGtk::SetTabBounds(TabGtk* tab, const gfx::Rect& bounds) {
  gfx::Rect bds = bounds;
  bds.set_x(gtk_util::MirroredLeftPointForRect(tabstrip_.get(), bounds));
  tab->SetBounds(bds);
  gtk_fixed_move(GTK_FIXED(tabstrip_.get()), tab->widget(),
                 bds.x(), bds.y());
}

bool TabStripGtk::CanPaintOnlyFavicons(const GdkRectangle* rects,
    int num_rects, std::vector<int>* tabs_to_paint) {
  // |rects| are sorted so we just need to scan from left to right and compare
  // it to the tab favicon positions from left to right.
  int t = 0;
  for (int r = 0; r < num_rects; ++r) {
    while (t < GetTabCount()) {
      TabGtk* tab = GetTabAt(t);
      if (GdkRectMatchesTabFaviconBounds(rects[r], tab) &&
          tab->ShouldShowIcon()) {
        tabs_to_paint->push_back(t);
        ++t;
        break;
      }
      ++t;
    }
  }
  return static_cast<int>(tabs_to_paint->size()) == num_rects;
}

void TabStripGtk::PaintOnlyFavicons(GdkEventExpose* event,
                                    const std::vector<int>& tabs_to_paint) {
  for (size_t i = 0; i < tabs_to_paint.size(); ++i)
    GetTabAt(tabs_to_paint[i])->PaintFaviconArea(event);
}

CustomDrawButton* TabStripGtk::MakeNewTabButton() {
  CustomDrawButton* button = new CustomDrawButton(IDR_NEWTAB_BUTTON,
      IDR_NEWTAB_BUTTON_P, IDR_NEWTAB_BUTTON_H, 0);

  // Let the middle mouse button initiate clicks as well.
  gtk_util::SetButtonTriggersNavigation(button->widget());
  g_signal_connect(button->widget(), "clicked",
                   G_CALLBACK(OnNewTabClickedThunk), this);
  GTK_WIDGET_UNSET_FLAGS(button->widget(), GTK_CAN_FOCUS);
  gtk_fixed_put(GTK_FIXED(tabstrip_.get()), button->widget(), 0, 0);

  return button;
}