Introduce media::TimeSource.

media/base/audio_renderer.h

Index: media/base/audio_renderer.h
diff --git a/media/base/audio_renderer.h b/media/base/audio_renderer.h
index 48ab6846b73ee2738c70ce9435454a7afa3aa873..faa4232c42c301e217f3163b2d75689c6b311f6b 100644
--- a/media/base/audio_renderer.h
+++ b/media/base/audio_renderer.h
@@ -11,12 +11,13 @@
 #include "media/base/buffering_state.h"
 #include "media/base/media_export.h"
 #include "media/base/pipeline_status.h"
+#include "media/base/time_source.h"
 
 namespace media {
 
 class DemuxerStream;
 
-class MEDIA_EXPORT AudioRenderer {
+class MEDIA_EXPORT AudioRenderer : public TimeSource {
  public:
   // First parameter is the current time that has been rendered.
   // Second parameter is the maximum time value that the clock cannot exceed.
@@ -30,8 +31,6 @@ class MEDIA_EXPORT AudioRenderer {
   //
   // |statistics_cb| is executed periodically with audio rendering stats.
   //
-  // |time_cb| is executed whenever time has advanced by way of audio rendering.
-  //
   // |buffering_state_cb| is executed when audio rendering has either run out of
   // data or has enough data to continue playback.
   //
@@ -41,19 +40,10 @@ class MEDIA_EXPORT AudioRenderer {
   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) = 0;
 
-  // Signal audio playback to start at the current rate. It is expected that
-  // |time_cb| will eventually start being run with time updates.
-  virtual void StartRendering() = 0;
-
-  // Signal audio playback to stop until further notice. It is expected that
-  // |time_cb| will no longer be run.
-  virtual void StopRendering() = 0;
-
   // Discard any audio data, executing |callback| when completed.
   //
   // Clients should expect |buffering_state_cb| to be called with
@@ -61,18 +51,14 @@ class MEDIA_EXPORT AudioRenderer {
   virtual void Flush(const base::Closure& callback) = 0;
 
   // Starts playback by reading from |stream| and decoding and rendering audio.
-  // |timestamp| is the media timestamp playback should start rendering from.
   //
   // Only valid to call after a successful Initialize() or Flush().
-  virtual void StartPlayingFrom(base::TimeDelta timestamp) = 0;
+  virtual void StartPlaying() = 0;
 
   // Stop all operations in preparation for being deleted, executing |callback|
   // when complete.
   virtual void Stop(const base::Closure& callback) = 0;
 
-  // Updates the current playback rate.
-  virtual void SetPlaybackRate(float playback_rate) = 0;
-
   // Sets the output volume.
   virtual void SetVolume(float volume) = 0;