Fix media timeline so that thumb never exceeds buffered data

media/base/filters.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Filters are connected in a strongly typed manner, with downstream filters
 // always reading data from upstream filters.  Upstream filters have no clue
 // who is actually reading from them, and return the results via callbacks.
 //
 //                         DemuxerStream(Video) <- VideoDecoder <- VideoRenderer
 // DataSource <- Demuxer <
@@ skipping 182 matching lines @@
   virtual int samples_per_second() = 0;
 
  protected:
   AudioDecoder();
   virtual ~AudioDecoder();
 };
 
 
 class MEDIA_EXPORT VideoRenderer : public Filter {
  public:
+  // Used to update the pipeline's clock time. The parameter is the time that
+  // the clock should not exceed.
+  typedef base::Callback<void(base::TimeDelta)> VideoTimeCB;
+
   // Initialize a VideoRenderer with the given VideoDecoder, executing the
-  // callback upon completion.
-  virtual void Initialize(VideoDecoder* decoder, const base::Closure& callback,
-                          const StatisticsCallback& stats_callback) = 0;
+  // |init_cb| upon completion.
+  virtual void Initialize(VideoDecoder* decoder, const base::Closure& init_cb,
+                          const StatisticsCallback& stats_callback,
+                          const VideoTimeCB& time_cb) = 0;
 
   // Returns true if this filter has received and processed an end-of-stream
   // buffer.
   virtual bool HasEnded() = 0;
 };
 
 
 class MEDIA_EXPORT AudioRenderer : public Filter {
  public:
+  // Used to update the pipeline's clock time. The first parameter is the
+  // current time, and the second parameter is the time that the clock must not
+  // exceed.
+  typedef base::Callback<void(base::TimeDelta, base::TimeDelta)> AudioTimeCB;
+
   // Initialize a AudioRenderer with the given AudioDecoder, executing the
   // |init_callback| upon completion. |underflow_callback| is called when the
   // renderer runs out of data to pass to the audio card during playback.
   // If the |underflow_callback| is called ResumeAfterUnderflow() must be called
   // to resume playback. Pause(), Seek(), or Stop() cancels the underflow
   // condition.
   virtual void Initialize(AudioDecoder* decoder,
                           const base::Closure& init_callback,
-                          const base::Closure& underflow_callback) = 0;
+                          const base::Closure& underflow_callback,
+                          const AudioTimeCB& time_cb) = 0;
 
   // Returns true if this filter has received and processed an end-of-stream
   // buffer.
   virtual bool HasEnded() = 0;
 
   // Sets the output volume.
   virtual void SetVolume(float volume) = 0;
 
   // Resumes playback after underflow occurs.
   // |buffer_more_audio| is set to true if you want to increase the size of the
   // decoded audio buffer.
   virtual void ResumeAfterUnderflow(bool buffer_more_audio) = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_FILTERS_H_