Implemented proper pause-then-seek behaviour for the media pipeline.

media/base/filters.h

 // Copyright (c) 2006-2009 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 70 matching lines @@
   virtual void set_message_loop(MessageLoop* message_loop) {
     DCHECK(message_loop);
     DCHECK(!message_loop_);
     message_loop_ = message_loop;
   }
 
   virtual MessageLoop* message_loop() {
     return message_loop_;
   }
 
+  // The pipeline has resumed playback.  Filters can continue requesting reads.
+  // Filters may implement this method if they need to respond to this call.
+  virtual void Play(FilterCallback* callback) {
+    if (callback) {
+      callback->Run();
+      delete callback;
+    }
+  }
+
+  // The pipeline has paused playback.  Filters should fulfill any existing read
+  // requests and then idle.  Filters may implement this method if they need to
+  // respond to this call.
+  virtual void Pause(FilterCallback* callback) {
+    if (callback) {
+      callback->Run();
+      delete callback;
+    }
+  }
+
   // The pipeline is being stopped either as a result of an error or because
   // the client called Stop().
   virtual void Stop() = 0;
 
   // The pipeline playback rate has been changed.  Filters may implement this
   // method if they need to respond to this call.
   virtual void SetPlaybackRate(float playback_rate) {}
 
   // Carry out any actions required to seek to the given time, executing the
   // callback upon completion.
@@ skipping 198 matching lines @@
   // callback upon completion.
   virtual void Initialize(AudioDecoder* decoder, FilterCallback* callback) = 0;
 
   // Sets the output volume.
   virtual void SetVolume(float volume) = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_FILTERS_H_