Revert of WebAudio: Remove AudioNode::RefType.

Source/modules/webaudio/AudioContext.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 249 matching lines @@
     // When the context goes away, there might still be some sources which haven't finished playing.
     // Make sure to dereference them here.
     void derefUnfinishedSourceNodes();
 
     RefPtrWillBeMember<AudioDestinationNode> m_destinationNode;
     RefPtrWillBeMember<AudioListener> m_listener;
 
     // Only accessed in the audio thread.
     Vector<AudioNode*> m_finishedNodes;
 
-    // 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.
-    // This RefPtr is connection reference. We must call AudioNode::
-    // makeConnection() after ref(), and call AudioNode::breakConnection()
-    // before deref().
-    Vector<RefPtr<AudioNode> > m_referencedNodes;
+    // We don't use RefPtr<AudioNode> here because AudioNode has a more complex ref() / deref() implementation
+    // with an optional argument for refType.  We need to use the special refType: RefTypeConnection
+    // Either accessed when the graph lock is held, or on the main thread when the audio thread has finished.
+    Vector<AudioNode*> m_referencedNodes;
 
     // Accumulate nodes which need to be deleted here.
     // This is copied to m_nodesToDelete at the end of a render cycle in handlePostRenderTasks(), where we're assured of a stable graph
     // state which will have no references to any of the nodes in m_nodesToDelete once the context lock is released
     // (when handlePostRenderTasks() has completed).
     Vector<AudioNode*> m_nodesMarkedForDeletion;
 
     // They will be scheduled for deletion (on the main thread) at the end of a render cycle (in realtime thread).
     Vector<AudioNode*> m_nodesToDelete;
     bool m_isDeletionScheduled;
@@ skipping 29 matching lines @@
     AsyncAudioDecoder m_audioDecoder;
 
     // This is considering 32 is large enough for multiple channels audio.
     // It is somewhat arbitrary and could be increased if necessary.
     enum { MaxNumberOfChannels = 32 };
 };
 
 } // WebCore
 
 #endif // AudioContext_h