Introduce media::TimeSource.

media/filters/audio_renderer_impl.h

Index: media/filters/audio_renderer_impl.h
diff --git a/media/filters/audio_renderer_impl.h b/media/filters/audio_renderer_impl.h
index cc06fa3bf58151d6225a770f4b270bf879802000..ae8f374f7cbda6f969f3d2990e045882887b14df 100644
--- a/media/filters/audio_renderer_impl.h
+++ b/media/filters/audio_renderer_impl.h
@@ -64,20 +64,23 @@ class MEDIA_EXPORT AudioRendererImpl
       AudioHardwareConfig* hardware_params);
   virtual ~AudioRendererImpl();
 
+  // TimeSource implementation.
+  virtual void StartTicking() OVERRIDE;
+  virtual void StopTicking() OVERRIDE;
+  virtual void SetPlaybackRate(float rate) OVERRIDE;
+  virtual void SetMediaTimestamp(base::TimeDelta timestamp) OVERRIDE;
+  virtual base::TimeDelta CurrentMediaTimestamp() OVERRIDE;
+
   // AudioRenderer implementation.
   virtual void Initialize(DemuxerStream* stream,
                           const PipelineStatusCB& init_cb,
                           const StatisticsCB& statistics_cb,
-                          const TimeCB& time_cb,
                           const BufferingStateCB& buffering_state_cb,
                           const base::Closure& ended_cb,
                           const PipelineStatusCB& error_cb) OVERRIDE;
-  virtual void StartRendering() OVERRIDE;
-  virtual void StopRendering() OVERRIDE;
   virtual void Flush(const base::Closure& callback) OVERRIDE;
   virtual void Stop(const base::Closure& callback) OVERRIDE;
-  virtual void SetPlaybackRate(float rate) OVERRIDE;
-  virtual void StartPlayingFrom(base::TimeDelta timestamp) OVERRIDE;
+  virtual void StartPlaying() OVERRIDE;
   virtual void SetVolume(float volume) OVERRIDE;
 
  private:
@@ -96,7 +99,7 @@ class MEDIA_EXPORT AudioRendererImpl
   //         |
   //         V            Decoders reset
   //      kFlushed <------------------ kFlushing
-  //         | StartPlayingFrom()         ^
+  //         | StartPlaying()             ^
   //         |                            |
   //         |                            | Flush()
   //         `---------> kPlaying --------'