bug 1198100 remove mNotificationMainThreadRunnable r=baku

If AddMainThreadListener() were called multiple times after
mFinishedNotificationSent is set then we'd get some extra NotifyRunnables but
NotifyMainThreadListeners() clears mMainThreadListeners anyway so we still get
only one notification per listener.

mNotificationMainThreadRunnable is an unnecessary optimization, so better not
to add storage to every MediaStream.

--HG--
extra : rebase_source : 7f0441d95134f1456058f668db30fb40bd9475c1

dom/media/MediaStreamGraph.cpp

@@ -2383,9 +2383,8 @@ MediaStream::AddMainThreadListener(MainThreadMediaStreamListener* aListener)
 
   mMainThreadListeners.AppendElement(aListener);
 
-  // If we have to send the notification or we have a runnable that will do it,
-  // let finish here.
-  if (!mFinishedNotificationSent || mNotificationMainThreadRunnable) {
+  // If it is not yet time to send the notification, then finish here.
+  if (!mFinishedNotificationSent) {
     return;
   }
 
@@ -2399,7 +2398,6 @@ MediaStream::AddMainThreadListener(MainThreadMediaStreamListener* aListener)
     NS_IMETHOD Run() override
     {
       MOZ_ASSERT(NS_IsMainThread());
-      mStream->mNotificationMainThreadRunnable = nullptr;
       mStream->NotifyMainThreadListeners();
       return NS_OK;
     }
@@ -2411,11 +2409,7 @@ MediaStream::AddMainThreadListener(MainThreadMediaStreamListener* aListener)
   };
 
   nsRefPtr<nsRunnable> runnable = new NotifyRunnable(this);
-  if (NS_WARN_IF(NS_FAILED(NS_DispatchToMainThread(runnable.forget())))) {
-    return;
-  }
-
-  mNotificationMainThreadRunnable = runnable;
+  NS_WARN_IF(NS_FAILED(NS_DispatchToMainThread(runnable.forget())));
 }
 
 void

dom/media/MediaStreamGraph.h

@@ -638,7 +638,6 @@ protected:
   TimeVarying<GraphTime,uint32_t,0> mExplicitBlockerCount;
   nsTArray<nsRefPtr<MediaStreamListener> > mListeners;
   nsTArray<MainThreadMediaStreamListener*> mMainThreadListeners;
-  nsRefPtr<nsRunnable> mNotificationMainThreadRunnable;
   nsTArray<TrackID> mDisabledTrackIDs;
 
   // Precomputed blocking status (over GraphTime).