Implement suspend/resume for AudioContext

Source/modules/webaudio/OfflineAudioDestinationNode.h

 /*
  * Copyright (C) 2011, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 34 matching lines @@
 
     virtual ~OfflineAudioDestinationNode();
 
     // AudioNode
     virtual void dispose() OVERRIDE;
     virtual void initialize() OVERRIDE;
     virtual void uninitialize() OVERRIDE;
 
     // AudioDestinationNode
     virtual void startRendering() OVERRIDE;
+    virtual void stop() OVERRIDE { };
 
     virtual float sampleRate()  const OVERRIDE { return m_renderTarget->sampleRate(); }
 
     virtual void trace(Visitor*) OVERRIDE;
 
 private:
     OfflineAudioDestinationNode(AudioContext*, AudioBuffer* renderTarget);
 
     // This AudioNode renders into this AudioBuffer.
     Member<AudioBuffer> m_renderTarget;
     // Temporary AudioBus for each render quantum.
     RefPtr<AudioBus> m_renderBus;
 
     // Rendering thread.
     OwnPtr<WebThread> m_renderThread;
     bool m_startedRendering;
     void offlineRender();
 
     // For completion callback on main thread.
     void notifyComplete();
 };
 
 } // namespace blink
 
 #endif // OfflineAudioDestinationNode_h