Don't run removeFinishedSourceNodes with the context lock.

third_party/WebKit/Source/modules/webaudio/BaseAudioContext.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 231 matching lines @@
   // When a source node has no more processing to do (has finished playing),
   // this method tells the context to release the corresponding node.
   void notifySourceNodeFinishedProcessing(AudioHandler*);
 
   // Called at the start of each render quantum.
   void handlePreRenderTasks(const AudioIOPosition& outputPosition);
 
   // Called at the end of each render quantum.
   void handlePostRenderTasks();
 
-  // Called periodically at the end of each render quantum to release finished
-  // source nodes.
-  void releaseFinishedSourceNodes();
+  // Called periodically at the end of each render quantum to release
+  // finished source nodes.  Updates m_finishedSourceNodes with nodes
+  // to be deleted.  Returns true if any node needs deletion.  Must be
+  // run from the audio thread.
+  bool releaseFinishedSourceNodes();
+
+  // Actually remove the nodes noted for deletion by
+  // releaseFinishedSourceNodes.  Must be run from the main thread,
+  // and must not be run with the context lock.
+  void removeFinishedSourceNodes();
 
   // Keeps track of the number of connections made.
   void incrementConnectionCount() {
     DCHECK(isMainThread());
     m_connectionCount++;
   }
 
   unsigned connectionCount() const { return m_connectionCount; }
 
   DeferredTaskHandler& deferredTaskHandler() const {
@@ skipping 107 matching lines @@
     AutoplayStatusCount
   };
 
   bool m_isCleared;
   void clear();
 
   // When the context goes away, there might still be some sources which
   // haven't finished playing.  Make sure to release them here.
   void releaseActiveSourceNodes();
 
-  void removeFinishedSourceNodes();
-
   // Listener for the PannerNodes
   Member<AudioListener> m_listener;
 
   // Only accessed in the audio thread.
   // These raw pointers are safe because AudioSourceNodes in
   // m_activeSourceNodes own them.
   Vector<AudioHandler*> m_finishedSourceHandlers;
 
   // List of source nodes. This is either accessed when the graph lock is
   // held, or on the main thread when the audio thread has finished.
@@ skipping 62 matching lines @@
   // It is somewhat arbitrary and could be increased if necessary.
   enum { MaxNumberOfChannels = 32 };
 
   Optional<AutoplayStatus> m_autoplayStatus;
   AudioIOPosition m_outputPosition;
 };
 
 }  // namespace blink
 
 #endif  // BaseAudioContext_h