Merge AudioRendererImpl and AudioRendererBase; add NullAudioSink

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 -> InitializeOnIOThread ------> AudioHostMsg_CreateStream -------->
+// Start -> CreateStreamOnIOThread -----> AudioHostMsg_CreateStream ------>
 //       <- OnStreamCreated <- AudioMsg_NotifyStreamCreated <-
 //       ---> PlayOnIOThread -----------> AudioHostMsg_PlayStream -------->
 //
 // Optionally Play() / Pause() sequences may occur:
 // Play -> PlayOnIOThread --------------> AudioHostMsg_PlayStream --------->
 // Pause -> PauseOnIOThread ------------> AudioHostMsg_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 =>
@@ skipping 52 matching lines @@
 
   // Minimal constructor where Initialize() must be called later.
   AudioDevice();
 
   AudioDevice(const media::AudioParameters& params, RenderCallback* callback);
 
   // AudioRendererSink implementation.
 
   virtual void Initialize(const media::AudioParameters& params,
                           RenderCallback* callback) OVERRIDE;
-  // Starts audio playback.
   virtual void Start() OVERRIDE;
-
-  // Stops audio playback.
   virtual void Stop() OVERRIDE;
-
-  // Resumes playback if currently paused.
   virtual void Play() OVERRIDE;
-
-  // Pauses playback.
-  // If |flush| is true then any pending audio that is in the pipeline
-  // (has not yet reached the hardware) will be discarded.  In this case,
-  // when Play() is later called, no previous pending audio will be
-  // rendered.
   virtual void Pause(bool flush) OVERRIDE;
-
-  // Sets the playback volume, with range [0.0, 1.0] inclusive.
-  // Returns |true| on success.
   virtual bool SetVolume(double volume) OVERRIDE;
-
-  // Gets the playback volume, with range [0.0, 1.0] inclusive.
   virtual void GetVolume(double* volume) OVERRIDE;
 
   // Methods called on IO thread ----------------------------------------------
   // AudioMessageFilter::Delegate methods, called by AudioMessageFilter.
   virtual void OnStateChanged(AudioStreamState state) OVERRIDE;
   virtual void OnStreamCreated(base::SharedMemoryHandle handle,
                                base::SyncSocket::Handle socket_handle,
                                uint32 length) OVERRIDE;
 
  private:
   // 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();
 
   // 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 InitializeOnIOThread(const media::AudioParameters& params);
+  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;
@@ skipping 28 matching lines @@
   // 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_