Disallow cross-thread Persistent<> read access.

third_party/WebKit/Source/modules/webaudio/ConvolverNode.h

 /*
  * Copyright (C) 2010, 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 45 matching lines @@
   void setNormalize(bool normalize) { m_normalize = normalize; }
 
  private:
   ConvolverHandler(AudioNode&, float sampleRate);
   double tailTime() const override;
   double latencyTime() const override;
 
   std::unique_ptr<Reverb> m_reverb;
   // This Persistent doesn't make a reference cycle including the owner
   // ConvolverNode.
-  Persistent<AudioBuffer> m_buffer;
+  // It is cross-thread, as it will be accessed by the audio and main threads.
+  CrossThreadPersistent<AudioBuffer> m_buffer;
 
   // This synchronizes dynamic changes to the convolution impulse response with
   // process().
   mutable Mutex m_processLock;
 
   // Normalize the impulse response or not. Must default to true.
   bool m_normalize;
 
   FRIEND_TEST_ALL_PREFIXES(ConvolverNodeTest, ReverbLifetime);
 };
@@ skipping 15 matching lines @@
  private:
   ConvolverNode(BaseAudioContext&);
   ConvolverHandler& convolverHandler() const;
 
   FRIEND_TEST_ALL_PREFIXES(ConvolverNodeTest, ReverbLifetime);
 };
 
 }  // namespace blink
 
 #endif  // ConvolverNode_h