Fix playback rate w/o audio. Remove unused SetPlaybackRate().

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 15 matching lines @@
  public:
   NullAudioSink();
 
   // AudioRendererSink implementation.
   virtual void Initialize(const AudioParameters& params,
                           RenderCallback* callback) OVERRIDE;
   virtual void Start() OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void Pause(bool flush) OVERRIDE;
   virtual void Play() OVERRIDE;
-  virtual void SetPlaybackRate(float rate) OVERRIDE;
   virtual bool SetVolume(double volume) OVERRIDE;
 
   // Enables audio frame hashing and reinitializes the MD5 context.  Must be
   // called prior to Initialize().
   void StartAudioHashForTesting();
 
   // Returns the MD5 hash of all audio frames seen since the last reset.
   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.
   std::vector<float*> audio_data_;
 
   AudioParameters params_;
   bool initialized_;
-  float playback_rate_;
   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_