Require use of AudioBus::create() to avoid ref-counting issues

Source/core/platform/audio/AudioFIFO.h

 /*
  * Copyright (C) 2012 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
@@ skipping 37 matching lines @@
     // Number of frames of data that are currently in the FIFO.
     size_t framesInFifo() const { return m_framesInFifo; }
 
 private:
     // Update the FIFO index by the step, with appropriate wrapping around the endpoint.
     int updateIndex(int index, int step) { return (index + step) % m_fifoLength; }
 
     void findWrapLengths(size_t index, size_t providerSize, size_t& part1Length, size_t& part2Length);
     
     // The FIFO itself. In reality, the FIFO is a circular buffer.
-    AudioBus m_fifoAudioBus;
+    RefPtr<AudioBus> m_fifoAudioBus;
 
     // The total available space in the FIFO.
     size_t m_fifoLength;
 
     // The number of actual elements in the FIFO
     size_t m_framesInFifo;
 
     // Where to start reading from the FIFO.
     size_t m_readIndex;
 
     // Where to start writing to the FIFO.
     size_t m_writeIndex;
 };
 
 } // namespace WebCore
 
 #endif // AudioFIFO.h