Fix media timeline so that thumb never exceeds buffered data

media/filters/audio_renderer_base.h

Index: media/filters/audio_renderer_base.h
diff --git a/media/filters/audio_renderer_base.h b/media/filters/audio_renderer_base.h
index 85549ee746d1c5edc6a70a919022f5832aabac8f..52aeda80d4a231ea6045a05b1d595dc6ae495c74 100644
--- a/media/filters/audio_renderer_base.h
+++ b/media/filters/audio_renderer_base.h
@@ -43,7 +43,8 @@ class MEDIA_EXPORT AudioRendererBase : public AudioRenderer {
   // AudioRenderer implementation.
   virtual void Initialize(AudioDecoder* decoder,
                           const PipelineStatusCB& init_callback,
-                          const base::Closure& underflow_callback) OVERRIDE;
+                          const base::Closure& underflow_callback,
+                          const AudioTimeCB& audio_time_cb) OVERRIDE;
   virtual bool HasEnded() OVERRIDE;
   virtual void ResumeAfterUnderflow(bool buffer_more_audio) OVERRIDE;
 
@@ -155,6 +156,8 @@ class MEDIA_EXPORT AudioRendererBase : public AudioRenderer {
 
   base::Closure underflow_callback_;
 
+  AudioTimeCB audio_time_cb_;
+
   base::TimeDelta seek_timestamp_;
 
   AudioDecoder::ReadCB read_cb_;