Move bulk of media::AudioRendererImpl::Render() logic to media thread.

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 2e29a9e82110adce8bccd546adcb3992a1323247..7871924d922913c9c5786ae7301a760b715c2e6f 100644
--- a/media/filters/audio_renderer_impl.h
+++ b/media/filters/audio_renderer_impl.h
@@ -33,6 +33,7 @@
 
 namespace base {
 class SingleThreadTaskRunner;
+class TickClock;
 }
 
 namespace media {
@@ -80,11 +81,7 @@ class MEDIA_EXPORT AudioRendererImpl
   virtual void StartPlayingFrom(base::TimeDelta timestamp) OVERRIDE;
   virtual void SetVolume(float volume) OVERRIDE;
 
-  // Allows injection of a custom time callback for non-realtime testing.
-  typedef base::Callback<base::TimeTicks()> NowCB;
-  void set_now_cb_for_testing(const NowCB& now_cb) {
-    now_cb_ = now_cb;
-  }
+  void SetTickClockForTesting(scoped_ptr<base::TickClock> tick_clock);
 
  private:
   friend class AudioRendererImplTest;
@@ -153,13 +150,25 @@ class MEDIA_EXPORT AudioRendererImpl
                      int audio_delay_milliseconds) OVERRIDE;
   virtual void OnRenderError() OVERRIDE;
 
+  // Contains result of the last call to Render(). Used to update |audio_clock_|
+  // and changes in buffering state.
+  struct RenderResult {
+    RenderResult();
+
+    base::TimeTicks ticks;
+    int requested_frames;
+    int delay_frames;
+    int frames_written;
+    float playback_rate;
+    base::TimeDelta endpoint_timestamp;
+  };
+  void DidRender(RenderResult result);
+
   // Helper methods that schedule an asynchronous read from the decoder as long
   // as there isn't a pending read.
   //
   // Must be called on |task_runner_|.
-  void AttemptRead();
   void AttemptRead_Locked();
-  bool CanRead_Locked();
   void ChangeState_Locked(State new_state);
 
   // Returns true if the data in the buffer is all before |start_timestamp_|.
@@ -188,7 +197,7 @@ class MEDIA_EXPORT AudioRendererImpl
   void OnConfigChange();
 
   // Updates |buffering_state_| and fires |buffering_state_cb_|.
-  void SetBufferingState_Locked(BufferingState buffering_state);
+  void SetBufferingState(BufferingState buffering_state);
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
@@ -221,8 +230,7 @@ class MEDIA_EXPORT AudioRendererImpl
   // Callback provided to Flush().
   base::Closure flush_cb_;
 
-  // Typically calls base::TimeTicks::Now() but can be overridden by a test.
-  NowCB now_cb_;
+  scoped_ptr<base::TickClock> tick_clock_;
 
   // After Initialize() has completed, all variables below must be accessed
   // under |lock_|. ------------------------------------------------------------