Web Audio: Unapply Oilpan to AudioSummingJunction.

Source/modules/webaudio/AudioSummingJunction.h

Index: Source/modules/webaudio/AudioSummingJunction.h
diff --git a/Source/modules/webaudio/AudioSummingJunction.h b/Source/modules/webaudio/AudioSummingJunction.h
index 920565ba675a174080251480ac09c0cf776eabfa..c3c66d95a608997bb5183090989aa03864309a3b 100644
--- a/Source/modules/webaudio/AudioSummingJunction.h
+++ b/Source/modules/webaudio/AudioSummingJunction.h
@@ -32,19 +32,17 @@
 
 namespace blink {
 
-class AudioContext;
 class AudioNodeOutput;
+class DeferredTaskHandler;
 
 // An AudioSummingJunction represents a point where zero, one, or more AudioNodeOutputs connect.
 
-class AudioSummingJunction : public GarbageCollectedFinalized<AudioSummingJunction> {
+class AudioSummingJunction {
 public:
     virtual ~AudioSummingJunction();
-    DECLARE_VIRTUAL_TRACE();
-    void dispose();
 
     // Can be called from any thread.
-    AudioContext* context() { return m_context.get(); }
+    DeferredTaskHandler& deferredTaskHandler() { return *m_deferredTaskHandler; }

[Raymond Toy, 2015/03/25 15:43:54]

Is it possible for m_deferredTaskHandler to ever be null?

[tkent, 2015/03/25 22:28:08]

It's never be null.  AudioSummingJunction constructor always take a valid
reference of DeferredTaskHandler, and AudioSummingJunction keeps a
RefPtr<DeferredTaskHandler>.

 
     // This must be called whenever we modify m_outputs.
     void changedOutputs();
@@ -61,9 +59,9 @@ public:
     virtual void didUpdate() = 0;
 
 protected:
-    explicit AudioSummingJunction(AudioContext*);
+    explicit AudioSummingJunction(DeferredTaskHandler&);
 
-    Member<AudioContext> m_context;
+    RefPtr<DeferredTaskHandler> m_deferredTaskHandler;
 
     // 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.