Move OnDecoderInitDone() from decoder to pipeline thread.

media/audio/null_audio_sink.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.
 
 #ifndef MEDIA_FILTERS_NULL_AUDIO_RENDERER_H_
 #define MEDIA_FILTERS_NULL_AUDIO_RENDERER_H_
 
 // NullAudioSink effectively uses an extra thread to "throw away" the
 // audio data at a rate resembling normal playback speed.  It's just like
 // decoding to /dev/null!
@@ skipping 32 matching lines @@
   std::string GetAudioHashForTesting();
 
  protected:
   virtual ~NullAudioSink();
 
  private:
   // Audio thread task that periodically calls FillBuffer() to consume
   // audio data.
   void FillBufferTask();
 
-  void SetPlaying(bool is_playing);
-
   // A buffer passed to FillBuffer to advance playback.
   scoped_ptr<AudioBus> audio_bus_;
 
   AudioParameters params_;
   bool initialized_;
   bool playing_;
   RenderCallback* callback_;
 
   // Separate thread used to throw away data.
   base::Thread thread_;
-  base::Lock lock_;
 
   // Controls whether or not a running MD5 hash is computed for audio frames.
   bool hash_audio_for_testing_;
   scoped_array<base::MD5Context> md5_channel_contexts_;
 
   DISALLOW_COPY_AND_ASSIGN(NullAudioSink);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_NULL_AUDIO_RENDERER_H_