First step towards moving AudioDevice from content/ to media/audio.

content/renderer/media/audio_device.h

 // 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.
 //
 // Audio rendering unit utilizing audio output stream provided by browser
 // process through IPC.
 //
 // Relationship of classes.
 //
 //  AudioOutputController                AudioDevice
 //           ^                                ^
 //           |                                |
 //           v               IPC              v
 //    AudioRendererHost  <---------> AudioMessageFilter
 //
 // Transportation of audio samples from the render to the browser process
 // is done by using shared memory in combination with a sync socket pair
 // to generate a low latency transport. The AudioDevice user registers an
 // AudioDevice::RenderCallback at construction and will be polled by the
 // AudioDevice for audio to be played out by the underlying audio layers.
 //
 // State sequences.
 //
 //            Task [IO thread]                  IPC [IO thread]
 //
-// Start -> CreateStreamOnIOThread -----> AudioHostMsg_CreateStream ------>
+// Start -> CreateStreamOnIOThread -----> CreateStream ------>
 //       <- OnStreamCreated <- AudioMsg_NotifyStreamCreated <-
-//       ---> PlayOnIOThread -----------> AudioHostMsg_PlayStream -------->
+//       ---> PlayOnIOThread -----------> PlayStream -------->
 //
 // Optionally Play() / Pause() sequences may occur:
-// Play -> PlayOnIOThread --------------> AudioHostMsg_PlayStream --------->
-// Pause -> PauseOnIOThread ------------> AudioHostMsg_PauseStream -------->
+// Play -> PlayOnIOThread --------------> PlayStream --------->
+// Pause -> PauseOnIOThread ------------> PauseStream -------->
 // (note that Play() / Pause() sequences before OnStreamCreated are
 //  deferred until OnStreamCreated, with the last valid state being used)
 //
 // AudioDevice::Render => audio transport on audio thread =>
 //                               |
-// Stop --> ShutDownOnIOThread -------->  AudioHostMsg_CloseStream -> Close
+// Stop --> ShutDownOnIOThread -------->  CloseStream -> Close
 //
 // This class utilizes several threads during its lifetime, namely:
 // 1. Creating thread.
 //    Must be the main render thread.
 // 2. Control thread (may be the main render thread or another thread).
 //    The methods: Start(), Stop(), Play(), Pause(), SetVolume()
 //    must be called on the same thread.
 // 3. IO thread (internal implementation detail - not exposed to public API)
 //    The thread within which this class receives all the IPC messages and
 //    IPC communications can only happen in this thread.
@@ skipping 14 matching lines @@
 #ifndef CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_H_
 #define CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_H_
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/shared_memory.h"
 #include "content/common/content_export.h"
 #include "content/renderer/media/audio_device_thread.h"
-#include "content/renderer/media/audio_message_filter.h"
 #include "content/renderer/media/scoped_loop_observer.h"
+#include "media/audio/audio_device_ipc.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_renderer_sink.h"
 
 namespace media {
 class AudioParameters;
 }
 
-namespace content {
-class AudioDeviceFactory;
-}
-
 class CONTENT_EXPORT AudioDevice
     : NON_EXPORTED_BASE(public media::AudioRendererSink),
-      public AudioMessageFilter::Delegate,
+      public media::AudioDeviceIPCDelegate,
       NON_EXPORTED_BASE(public ScopedLoopObserver) {
  public:
   // Methods called on main render thread -------------------------------------
 
   // AudioRendererSink implementation.
   virtual void Initialize(const media::AudioParameters& params,
                           RenderCallback* callback) OVERRIDE;
   virtual void Start() OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void Play() OVERRIDE;
   virtual void Pause(bool flush) OVERRIDE;
   virtual bool SetVolume(double volume) OVERRIDE;
 
   // Methods called on IO thread ----------------------------------------------
   // AudioMessageFilter::Delegate methods, called by AudioMessageFilter.
-  virtual void OnStateChanged(AudioStreamState state) OVERRIDE;
+  virtual void OnStateChanged(media::AudioStreamState state) OVERRIDE;
   virtual void OnStreamCreated(base::SharedMemoryHandle handle,
                                base::SyncSocket::Handle socket_handle,
                                uint32 length) OVERRIDE;
 
- protected:
-  friend class content::AudioDeviceFactory;
-
   // Creates an uninitialized AudioDevice. Clients must call Initialize()
-  // before using.  The constructor is protected to ensure that the
-  // AudioDeviceFactory is always used for construction in Chrome.
-  // Tests should use a test class that inherits from AudioDevice to gain
-  // access to the constructor.
+  // before using.
   // TODO(tommi): When all dependencies on |content| have been removed
   // from AudioDevice, move this class over to media/audio.
-  explicit AudioDevice(const scoped_refptr<base::MessageLoopProxy>& io_loop);
+  AudioDevice(media::AudioDeviceIPC* ipc,
+      const scoped_refptr<base::MessageLoopProxy>& io_loop);
 
+ protected:
   // Magic required by ref_counted.h to avoid any code deleting the object
   // accidentally while there are references to it.
   friend class base::RefCountedThreadSafe<AudioDevice>;
   virtual ~AudioDevice();
 
  private:
   // Methods called on IO thread ----------------------------------------------
   // The following methods are tasks posted on the IO thread that needs to
   // be executed on that thread. They interact with AudioMessageFilter and
   // sends IPC messages on that thread.
   void CreateStreamOnIOThread(const media::AudioParameters& params);
   void PlayOnIOThread();
   void PauseOnIOThread(bool flush);
   void ShutDownOnIOThread();
   void SetVolumeOnIOThread(double volume);
 
-  void Send(IPC::Message* message);
-
   // MessageLoop::DestructionObserver implementation for the IO loop.
   // If the IO loop dies before we do, we shut down the audio thread from here.
   virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
 
   media::AudioParameters audio_parameters_;
 
   RenderCallback* callback_;
 
-  // Cached audio message filter (lives on the main render thread).
-  scoped_refptr<AudioMessageFilter> filter_;
+  // A pointer to the IPC layer that takes care of sending requests over to
+  // the AudioRendererHost.
+  media::AudioDeviceIPC* ipc_;
 
   // Our stream ID on the message filter. Only accessed on the IO thread.
   // Must only be modified on the IO thread.
-  int32 stream_id_;
+  int stream_id_;
 
   // State of Play() / Pause() calls before OnStreamCreated() is called.
   bool play_on_start_;
 
   // Set to |true| when OnStreamCreated() is called.
   // Set to |false| when ShutDownOnIOThread() is called.
   // This is for use with play_on_start_ to track Play() / Pause() state.
   // Must only be touched from the IO thread.
   bool is_started_;
 
   // Our audio thread callback class.  See source file for details.
   class AudioThreadCallback;
 
   // In order to avoid a race between OnStreamCreated and Stop(), we use this
   // guard to control stopping and starting the audio thread.
   base::Lock audio_thread_lock_;
   AudioDeviceThread audio_thread_;
   scoped_ptr<AudioDevice::AudioThreadCallback> audio_callback_;
 
 
   DISALLOW_COPY_AND_ASSIGN(AudioDevice);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_H_