Bug 1178261 - make BroadcastChannel CC skippable, r=smaug

dom/broadcastchannel/BroadcastChannel.h

@@ -105,6 +105,11 @@ private:
 
   void UpdateMustKeepAlive();
 
+  bool IsCertainlyAliveForCC() const override
+  {
+    return mIsKeptAlive;
+  }
+
   nsRefPtr<BroadcastChannelChild> mActor;
   nsTArray<nsRefPtr<BroadcastChannelMessage>> mPendingMessages;
 

dom/events/DOMEventTargetHelper.cpp

@@ -48,10 +48,14 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(DOMEventTargetHelper)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_BEGIN(DOMEventTargetHelper)
-  if (tmp->IsBlack()) {
+  if (tmp->IsBlack() || tmp->IsCertainlyAliveForCC()) {
     if (tmp->mListenerManager) {
       tmp->mListenerManager->MarkForCC();
     }
+    if (!tmp->IsBlack() && tmp->PreservingWrapper()) {
+      // This marks the wrapper black.
+      tmp->GetWrapper();
+    }
     return true;
   }
 NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_END

dom/events/DOMEventTargetHelper.h

@@ -167,6 +167,14 @@ protected:
 
   nsresult WantsUntrusted(bool* aRetVal);
 
+  // If this method returns true your object is kept alive until it returns
+  // false. You can use this method instead using
+  // NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_BEGIN macro.
+  virtual bool IsCertainlyAliveForCC() const
+  {
+    return false;
+  }
+
   nsRefPtr<EventListenerManager> mListenerManager;
   // Make |event| trusted and dispatch |aEvent| to |this|.
   nsresult DispatchTrustedEvent(nsIDOMEvent* aEvent);

dom/messagechannel/MessagePort.cpp

@@ -192,29 +192,6 @@ MessagePortBase::MessagePortBase()
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(MessagePort)
 
-NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_BEGIN(MessagePort)
-  bool isBlack = tmp->IsBlack();
-  if (isBlack || tmp->mIsKeptAlive) {
-    if (tmp->mListenerManager) {
-      tmp->mListenerManager->MarkForCC();
-    }
-    if (!isBlack && tmp->PreservingWrapper()) {
-      // This marks the wrapper black.
-      tmp->GetWrapper();
-    }
-    return true;
-  }
-NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_END
-
-NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_BEGIN(MessagePort)
-  return tmp->
-    IsBlackAndDoesNotNeedTracing(static_cast<DOMEventTargetHelper*>(tmp));
-NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_IN_CC_END
-
-NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_BEGIN(MessagePort)
-  return tmp->IsBlack();
-NS_IMPL_CYCLE_COLLECTION_CAN_SKIP_THIS_END
-
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(MessagePort,
                                                 MessagePortBase)
   if (tmp->mDispatchRunnable) {
@@ -235,10 +212,6 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(MessagePort,
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mUnshippedEntangledPort);
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
-NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(MessagePort,
-                                               MessagePortBase)
-NS_IMPL_CYCLE_COLLECTION_TRACE_END
-
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(MessagePort)
   NS_INTERFACE_MAP_ENTRY(nsIIPCBackgroundChildCreateCallback)
   NS_INTERFACE_MAP_ENTRY(nsIObserver)

dom/messagechannel/MessagePort.h

@@ -75,8 +75,8 @@ public:
   NS_DECL_NSIIPCBACKGROUNDCHILDCREATECALLBACK
   NS_DECL_NSIOBSERVER
   NS_DECL_ISUPPORTS_INHERITED
-  NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_INHERITED(MessagePort,
-                                                                   DOMEventTargetHelper)
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(MessagePort,
+                                           MessagePortBase)
 
   static already_AddRefed<MessagePort>
   Create(nsPIDOMWindow* aWindow, const nsID& aUUID,
@@ -177,6 +177,11 @@ private:
   // We release the object when the port is closed or disentangled.
   void UpdateMustKeepAlive();
 
+  bool IsCertainlyAliveForCC() const override
+  {
+    return mIsKeptAlive;
+  }
+
   nsAutoPtr<workers::WorkerFeature> mWorkerFeature;
 
   nsRefPtr<DispatchEventRunnable> mDispatchRunnable;