Merge AudioRendererImpl and AudioRendererBase; add NullAudioSink

media/base/audio_renderer_sink.h

Index: media/base/audio_renderer_sink.h
diff --git a/media/base/audio_renderer_sink.h b/media/base/audio_renderer_sink.h
index 01eb18533587bdcd7b243a57c5402ca43cfb6cff..49ddbf540ce131ca321744ec41ee9d72f5e7df32 100644
--- a/media/base/audio_renderer_sink.h
+++ b/media/base/audio_renderer_sink.h
@@ -28,9 +28,9 @@ class AudioRendererSink
     // continuous stream). That actual number of frames is passed to host
     // together with PCM audio data and host is free to use or ignore it.
     // TODO(crogers): use base:Callback instead.
-    virtual size_t Render(const std::vector<float*>& audio_data,
-                          size_t number_of_frames,
-                          size_t audio_delay_milliseconds) = 0;
+    virtual int Render(const std::vector<float*>& audio_data,
+                       int number_of_frames,
+                       int audio_delay_milliseconds) = 0;
 
     // Signals an error has occurred.
     virtual void OnRenderError() = 0;
@@ -58,6 +58,10 @@ class AudioRendererSink
   // Resumes playback after calling Pause().
   virtual void Play() = 0;
 
+  // Called to inform the sink of a change in playback rate. Override if
+  // subclass needs the playback rate.
+  virtual void SetPlaybackRate(float rate) {};
+
   // Sets the playback volume, with range [0.0, 1.0] inclusive.
   // Returns |true| on success.
   virtual bool SetVolume(double volume) = 0;