Backed out changeset efa6394f2a4a (bug 1453925) for mochitest failures on test_broadcastchannel_worker_alive.html. a=backout

dom/broadcastchannel/BroadcastChannel.cpp

@@ -125,6 +125,48 @@ private:
   ErrorResult& mRv;
 };
 
+class BCPostMessageRunnable final : public nsIRunnable,
+                                    public nsICancelableRunnable
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  BCPostMessageRunnable(BroadcastChannelChild* aActor,
+                        BroadcastChannelMessage* aData)
+    : mActor(aActor)
+    , mData(aData)
+  {
+    MOZ_ASSERT(mActor);
+  }
+
+  NS_IMETHOD Run() override
+  {
+    MOZ_ASSERT(mActor);
+    if (mActor->IsActorDestroyed()) {
+      return NS_OK;
+    }
+
+    ClonedMessageData message;
+    mData->BuildClonedMessageDataForBackgroundChild(mActor->Manager(), message);
+    mActor->SendPostMessage(message);
+    return NS_OK;
+  }
+
+  nsresult Cancel() override
+  {
+    mActor = nullptr;
+    return NS_OK;
+  }
+
+private:
+  ~BCPostMessageRunnable() {}
+
+  RefPtr<BroadcastChannelChild> mActor;
+  RefPtr<BroadcastChannelMessage> mData;
+};
+
+NS_IMPL_ISUPPORTS(BCPostMessageRunnable, nsICancelableRunnable, nsIRunnable)
+
 class CloseRunnable final : public nsIRunnable,
                             public nsICancelableRunnable
 {
@@ -356,6 +398,14 @@ BroadcastChannel::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
     return;
   }
 
+  PostMessageInternal(aCx, aMessage, aRv);
+}
+
+void
+BroadcastChannel::PostMessageInternal(JSContext* aCx,
+                                      JS::Handle<JS::Value> aMessage,
+                                      ErrorResult& aRv)
+{
   RefPtr<BroadcastChannelMessage> data = new BroadcastChannelMessage();
 
   data->Write(aCx, aMessage, aRv);
@@ -363,11 +413,20 @@ BroadcastChannel::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
     return;
   }
 
+  PostMessageData(data);
+}
+
+void
+BroadcastChannel::PostMessageData(BroadcastChannelMessage* aData)
+{
   RemoveDocFromBFCache();
 
-  ClonedMessageData message;
-  data->BuildClonedMessageDataForBackgroundChild(mActor->Manager(), message);
-  mActor->SendPostMessage(message);
+  RefPtr<BCPostMessageRunnable> runnable =
+    new BCPostMessageRunnable(mActor, aData);
+
+  if (NS_FAILED(NS_DispatchToCurrentThread(runnable))) {
+    NS_WARNING("Failed to dispatch to the current thread!");
+  }
 }
 
 void

dom/broadcastchannel/tests/test_event_listener_leaks.html

@@ -23,10 +23,10 @@ async function useBroadcastChannel(contentWindow) {
   count += 1;
   const name = `test_event_listener_leaks-${count}`;
 
-  let bc = new contentWindow.BroadcastChannel(name);
   let outer = new BroadcastChannel(name);
   outer.postMessage('foo');
 
+  let bc = new contentWindow.BroadcastChannel(name);
   await new Promise(resolve => {
     bc.onmessage = e => {
       contentWindow.messageCount += 1;