Bug 859600 - Make AudioContext an EventTarget; r=smaug

Author: Ehsan Akhgari

content/media/webaudio/AudioContext.cpp

@@ -29,20 +29,21 @@ const unsigned MAX_SCRIPT_PROCESSOR_CHANNELS = 10000;
 namespace mozilla {
 namespace dom {
 
-NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_3(AudioContext,
-                                        mWindow, mDestination, mListener)
+NS_IMPL_CYCLE_COLLECTION_2(AudioContext, mDestination, mListener)
 
-NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(AudioContext, AddRef)
-NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(AudioContext, Release)
+NS_IMPL_ADDREF_INHERITED(AudioContext, nsDOMEventTargetHelper)
+NS_IMPL_RELEASE_INHERITED(AudioContext, nsDOMEventTargetHelper)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(AudioContext)
+NS_INTERFACE_MAP_END_INHERITING(nsDOMEventTargetHelper)
 
 static uint8_t gWebAudioOutputKey;
 
 AudioContext::AudioContext(nsPIDOMWindow* aWindow)
-  : mWindow(aWindow)
-  , mDestination(new AudioDestinationNode(this, MediaStreamGraph::GetInstance()))
+  : mDestination(new AudioDestinationNode(this, MediaStreamGraph::GetInstance()))
 {
   // Actually play audio
   mDestination->Stream()->AddAudioOutput(&gWebAudioOutputKey);
+  nsDOMEventTargetHelper::BindToOwner(aWindow);
   SetIsDOMBinding();
 
   mPannerNodes.Init();

content/media/webaudio/AudioContext.h

@@ -7,7 +7,7 @@
 #ifndef AudioContext_h_
 #define AudioContext_h_
 
-#include "nsWrapperCache.h"
+#include "nsDOMEventTargetHelper.h"
 #include "nsCycleCollectionParticipant.h"
 #include "mozilla/Attributes.h"
 #include "nsCOMPtr.h"
@@ -51,19 +51,20 @@ class GlobalObject;
 class PannerNode;
 class ScriptProcessorNode;
 
-class AudioContext MOZ_FINAL : public nsWrapperCache,
+class AudioContext MOZ_FINAL : public nsDOMEventTargetHelper,
                                public EnableWebAudioCheck
 {
   explicit AudioContext(nsPIDOMWindow* aParentWindow);
   ~AudioContext();
 
 public:
-  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(AudioContext)
-  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(AudioContext)
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(AudioContext,
+                                           nsDOMEventTargetHelper)
 
   nsPIDOMWindow* GetParentObject() const
   {
-    return mWindow;
+    return GetOwner();
   }
 
   void Shutdown();
@@ -164,7 +165,6 @@ class AudioContext MOZ_FINAL : public nsWrapperCache,
   friend struct ::mozilla::WebAudioDecodeJob;
 
 private:
-  nsCOMPtr<nsPIDOMWindow> mWindow;
   nsRefPtr<AudioDestinationNode> mDestination;
   nsRefPtr<AudioListener> mListener;
   MediaBufferDecoder mDecoder;

content/media/webaudio/test/test_AudioContext.html

@@ -15,6 +15,7 @@
   var ac = new AudioContext();
   ok(ac, "Create a AudioContext object");
   is(ac.sampleRate, 48000, "Correct sample rate");
+  ok(ac instanceof EventTarget, "AudioContexts must be EventTargets");
   SpecialPowers.clearUserPref("media.webaudio.enabled");
   SimpleTest.finish();
 });

dom/webidl/AudioContext.webidl

@@ -14,7 +14,7 @@ callback DecodeSuccessCallback = void (AudioBuffer decodedData);
 callback DecodeErrorCallback = void ();
 
 [Constructor, PrefControlled]
-interface AudioContext {
+interface AudioContext : EventTarget {
 
     readonly attribute AudioDestinationNode destination;
     readonly attribute float sampleRate;