Make AudioOutputDevice restartable and reinitializable

media/audio/audio_output_device.h

Index: media/audio/audio_output_device.h
diff --git a/media/audio/audio_output_device.h b/media/audio/audio_output_device.h
index 532f45fe4a13eeb6b8b2884292e28652da3690f1..cee37063ce0589b044b2e87593cb73c0962c2624 100644
--- a/media/audio/audio_output_device.h
+++ b/media/audio/audio_output_device.h
@@ -80,7 +80,8 @@
 namespace media {
 
 class MEDIA_EXPORT AudioOutputDevice
-    : NON_EXPORTED_BASE(public AudioRendererSink),
+    : NON_EXPORTED_BASE(public RestartableAudioRendererSink),
+      NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback),
       NON_EXPORTED_BASE(public AudioOutputIPCDelegate),
       NON_EXPORTED_BASE(public ScopedTaskRunnerObserver) {
  public:
@@ -97,7 +98,7 @@ class MEDIA_EXPORT AudioOutputDevice
 
   // AudioRendererSink implementation.
   void Initialize(const AudioParameters& params,
-                  RenderCallback* callback) override;
+                  AudioRendererSink::RenderCallback* callback) override;
   void Start() override;
   void Stop() override;
   void Play() override;
@@ -134,15 +135,24 @@ class MEDIA_EXPORT AudioOutputDevice
     PLAYING,  // Playing back.  Can Pause()/Stop().
   };
 
+  // media::AudioRendererSink::RenderCallback implementation.
+  // These two functions are called on the audio worker thread.
+  int Render(media::AudioBus* audio_bus,
+             uint32_t frames_delayed,
+             uint32_t frames_skipped) override;
+  void OnRenderError() override;
+
   // Methods called on IO thread ----------------------------------------------
   // The following methods are tasks posted on the IO thread that need to
   // be executed on that thread.  They use AudioOutputIPC to send IPC messages
   // upon state changes.
   void RequestDeviceAuthorizationOnIOThread();
-  void CreateStreamOnIOThread(const AudioParameters& params);
+  void InitializeOnIOThread(const AudioParameters& params,
+                            AudioRendererSink::RenderCallback* callback);
+  void CreateStreamOnIOThread();
   void PlayOnIOThread();
   void PauseOnIOThread();
-  void ShutDownOnIOThread();
+  void StopOnIOThread();
   void SetVolumeOnIOThread(double volume);
 
   // base::MessageLoop::DestructionObserver implementation for the IO loop.
@@ -151,7 +161,8 @@ class MEDIA_EXPORT AudioOutputDevice
 
   AudioParameters audio_parameters_;
 
-  RenderCallback* callback_;
+  base::Lock callback_lock_;
+  AudioRendererSink::RenderCallback* callback_;
 
   // A pointer to the IPC layer that takes care of sending requests over to
   // the AudioRendererHost.  Only valid when state_ != IPC_CLOSED and must only