Move webaudio to oilpan

Source/modules/webaudio/AudioNode.h

Index: Source/modules/webaudio/AudioNode.h
diff --git a/Source/modules/webaudio/AudioNode.h b/Source/modules/webaudio/AudioNode.h
index 5ebe221ee62803656bb0fb4e6301e83faf4d0502..a747aa94db853485d4240be6574a20d903f56b5d 100644
--- a/Source/modules/webaudio/AudioNode.h
+++ b/Source/modules/webaudio/AudioNode.h
@@ -50,7 +50,7 @@ class ExceptionState;
 // An AudioDestinationNode has one input and no outputs and represents the final destination to the audio hardware.
 // Most processing nodes such as filters will have one input and one output, although multiple inputs and outputs are possible.
 
-class AudioNode : public ScriptWrappable, public EventTargetWithInlineData {
+class AudioNode : public NoBaseWillBeGarbageCollectedFinalized<AudioNode>, public ScriptWrappable, public EventTargetWithInlineData {

[haraken, 2014/04/08 06:02:08]

Add a comment about why this doesn't need to be RefCountedGarbageCollected.

[keishi, 2014/04/21 17:10:11]

Done.

 public:
     enum { ProcessingSizeInFrames = 128 };
 
@@ -179,6 +179,12 @@ public:
     virtual const AtomicString& interfaceName() const OVERRIDE FINAL;
     virtual ExecutionContext* executionContext() const OVERRIDE FINAL;
 
+    virtual void trace(Visitor*);
+
+#if ENABLE(OILPAN)
+    void clearKeepAlive();
+#endif
+
 protected:
     // Inputs and outputs must be created before the AudioNode is initialized.
     void addInput(PassOwnPtr<AudioNodeInput>);
@@ -195,11 +201,26 @@ protected:
 private:
     volatile bool m_isInitialized;
     NodeType m_nodeType;
-    RefPtr<AudioContext> m_context;
+    RefPtrWillBeMember<AudioContext> m_context;
     float m_sampleRate;
     Vector<OwnPtr<AudioNodeInput> > m_inputs;
     Vector<OwnPtr<AudioNodeOutput> > m_outputs;
 
+#if ENABLE(OILPAN)
+    // AudioNodes are still reference counted but they are in the
+    // oilpan heap because the ScriptProcessorNode is an EventTarget.
+    // This self-persistent keeps the object from being deleted
+    // until the reference count reaches zero.

[haraken, 2014/04/08 06:02:08]

EventTarget is not yet on-heap, so this comment doesn't make much sense. The
comment could be something like:

"AudioNodes are in the oilpan heap but they are still reference counted at the
same time. This is because we are not allowed to stop the audio thread and thus
the audio thread cannot allocate objects in the oilpan heap.

The m_keepAlive handle is used to keep a persistent reference to this AudioNode
while someone has a reference to this AudioNode through a RefPtr."

[keishi, 2014/04/21 17:10:11]

Done.

+    //
+    // It is safe to drop the self-persistent when the ref count
+    // of a ScriptProcessorNode reaches zero. At that point, the
+    // ScriptProcessor node is removed from the AudioContext and
+    // it cannot be reattached. Therefore, the reference count
+    // will not go above zero again.

[haraken, 2014/04/08 06:02:08]

I'd put this comment in clearKeepAlive() in the cpp file.

[keishi, 2014/04/21 17:10:11]

Done.

+    GC_PLUGIN_IGNORE("http://crbug.com/353083")
+    OwnPtr<Persistent<AudioNode> > m_keepAlive;
+#endif
+
     double m_lastProcessingTime;
     double m_lastNonSilentTime;