Oilpan: WebAudio: Apply the weak HashMap pattern to remove an entry from AudioContext::m_dirtyAudio…

Source/modules/webaudio/AudioSummingJunction.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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 45 matching lines @@
     unsigned numberOfRenderingConnections() const { return m_renderingOutputs.size(); }
     AudioNodeOutput* renderingOutput(unsigned i) { return m_renderingOutputs[i]; }
     bool isConnected() const { return numberOfRenderingConnections() > 0; }
 
     virtual bool canUpdateState() = 0;
     virtual void didUpdate() = 0;
 
 protected:
     explicit AudioSummingJunction(AudioContext*);
 
-    // Oilpan: m_context can be null only in the destructor because
-    // AudioSummingJunction objects are owned by AudioNodes, and AudioNodes have
-    // strong references to AudioContext.
-    // Theorically this should be a strong reference and AudioContext::
-    // m_dirtySummingJunctions should be HeapHashSet<WeakMember<
-    // AudioSummingJunction>>, but we can't do them because the map is modified
-    // in an audio rendering thread, which has no GC support. We need to remove
-    // an AudioSummingJunction from AudioContext in ~AudioSummingJunction, and
-    // this WeakMember<> makes it possible though we can't do it with Member<>.
-    RefPtrWillBeWeakMember<AudioContext> m_context;
+    RefPtrWillBeMember<AudioContext> m_context;
 
     // m_outputs contains the AudioNodeOutputs representing current connections which are not disabled.
     // The rendering code should never use this directly, but instead uses m_renderingOutputs.
     HashSet<AudioNodeOutput*> m_outputs;
 
     // m_renderingOutputs is a copy of m_outputs which will never be modified during the graph rendering on the audio thread.
     // This is the list which is used by the rendering code.
     // Whenever m_outputs is modified, the context is told so it can later update m_renderingOutputs from m_outputs at a safe time.
     // Most of the time, m_renderingOutputs is identical to m_outputs.
     Vector<AudioNodeOutput*> m_renderingOutputs;
 
     // m_renderingStateNeedUpdating keeps track if m_outputs is modified.
     bool m_renderingStateNeedUpdating;
 };
 
 } // namespace WebCore
 
 #endif // AudioSummingJunction_h