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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
      6 #define CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
      7 
      8 #include <utility>
      9 #include <vector>
     10 
     11 #include "base/callback_forward.h"
     12 #include "base/memory/ref_counted.h"
     13 #include "base/memory/scoped_ptr.h"
     14 #include "base/memory/shared_memory.h"
     15 #include "base/memory/weak_ptr.h"
     16 #include "base/message_loop/message_loop_proxy.h"
     17 #include "base/synchronization/lock.h"
     18 #include "base/system_monitor/system_monitor.h"
     19 #include "content/common/content_export.h"
     20 
     21 namespace base {
     22 class MessageLoopProxy;
     23 class Thread;
     24 }
     25 
     26 namespace content {
     27 
     28 class GamepadDataFetcher;
     29 struct GamepadHardwareBuffer;
     30 
     31 class CONTENT_EXPORT GamepadProvider :
     32   public base::SystemMonitor::DevicesChangedObserver {
     33  public:
     34   GamepadProvider();
     35 
     36   // Manually specifies the data fetcher. Used for testing.
     37   explicit GamepadProvider(scoped_ptr<GamepadDataFetcher> fetcher);
     38 
     39   virtual ~GamepadProvider();
     40 
     41   // Returns the shared memory handle of the gamepad data duplicated into the
     42   // given process.
     43   base::SharedMemoryHandle GetSharedMemoryHandleForProcess(
     44       base::ProcessHandle renderer_process);
     45 
     46   // Pause and resume the background polling thread. Can be called from any
     47   // thread.
     48   void Pause();
     49   void Resume();
     50 
     51   // Registers the given closure for calling when the user has interacted with
     52   // the device. This callback will only be issued once.
     53   void RegisterForUserGesture(const base::Closure& closure);
     54 
     55   // base::SystemMonitor::DevicesChangedObserver implementation.
     56   virtual void OnDevicesChanged(base::SystemMonitor::DeviceType type) OVERRIDE;
     57 
     58  private:
     59   void Initialize(scoped_ptr<GamepadDataFetcher> fetcher);
     60 
     61   // Method for setting up the platform-specific data fetcher. Takes ownership
     62   // of |fetcher|.
     63   void DoInitializePollingThread(scoped_ptr<GamepadDataFetcher> fetcher);
     64 
     65   // Method for sending pause hints to the low-level data fetcher. Runs on
     66   // polling_thread_.
     67   void SendPauseHint(bool paused);
     68 
     69   // Method for polling a GamepadDataFetcher. Runs on the polling_thread_.
     70   void DoPoll();
     71   void ScheduleDoPoll();
     72 
     73   GamepadHardwareBuffer* SharedMemoryAsHardwareBuffer();
     74 
     75   // Checks the gamepad state to see if the user has interacted with it.
     76   void CheckForUserGesture();
     77 
     78   enum { kDesiredSamplingIntervalMs = 16 };
     79 
     80   // Keeps track of when the background thread is paused. Access to is_paused_
     81   // must be guarded by is_paused_lock_.
     82   base::Lock is_paused_lock_;
     83   bool is_paused_;
     84 
     85   // Keep track of when a polling task is schedlued, so as to prevent us from
     86   // accidentally scheduling more than one at any time, when rapidly toggling
     87   // |is_paused_|.
     88   bool have_scheduled_do_poll_;
     89 
     90   // Lists all observers registered for user gestures, and the thread which
     91   // to issue the callbacks on. Since we always issue the callback on the
     92   // thread which the registration happened, and this class lives on the I/O
     93   // thread, the message loop proxies will normally just be the I/O thread.
     94   // However, this will be the main thread for unit testing.
     95   base::Lock user_gesture_lock_;
     96   struct ClosureAndThread {
     97     ClosureAndThread(const base::Closure& c,
     98                      const scoped_refptr<base::MessageLoopProxy>& m);
     99     ~ClosureAndThread();
    100 
    101     base::Closure closure;
    102     scoped_refptr<base::MessageLoopProxy> message_loop;
    103   };
    104   typedef std::vector<ClosureAndThread> UserGestureObserverVector;
    105   UserGestureObserverVector user_gesture_observers_;
    106 
    107   // Updated based on notification from SystemMonitor when the system devices
    108   // have been updated, and this notification is passed on to the data fetcher
    109   // to enable it to avoid redundant (and possibly expensive) is-connected
    110   // tests. Access to devices_changed_ must be guarded by
    111   // devices_changed_lock_.
    112   base::Lock devices_changed_lock_;
    113   bool devices_changed_;
    114 
    115   // When polling_thread_ is running, members below are only to be used
    116   // from that thread.
    117   scoped_ptr<GamepadDataFetcher> data_fetcher_;
    118   base::SharedMemory gamepad_shared_memory_;
    119 
    120   // Polling is done on this background thread.
    121   scoped_ptr<base::Thread> polling_thread_;
    122 
    123   static GamepadProvider* instance_;
    124 
    125   DISALLOW_COPY_AND_ASSIGN(GamepadProvider);
    126 };
    127 
    128 }  // namespace content
    129 
    130 #endif  // CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
    131