Bug 827913: remove no-longer-correct MOZ_ASSERT in getUserMedia r=derf

dom/media/MediaManager.cpp

@@ -1068,7 +1068,9 @@ MediaManager::OnNavigation(uint64_t aWindowID)
   for (uint32_t i = 0; i < length; i++) {
     nsRefPtr<GetUserMediaCallbackMediaStreamListener> listener =
       listeners->ElementAt(i);
-    listener->Invalidate();
+    if (listener->Stream()) { // aka HasBeenActivate()ed
+      listener->Invalidate();
+    }
     listener->Remove();
   }
   listeners->Clear();
@@ -1252,7 +1254,7 @@ void
 GetUserMediaCallbackMediaStreamListener::NotifyFinished(MediaStreamGraph* aGraph)
 {
   mFinished = true;
-  Invalidate();
+  Invalidate(); // we know it's been activated
   NS_DispatchToMainThread(new GetUserMediaListenerRemove(mWindowID, this));
 }
 

dom/media/MediaManager.h

@@ -104,7 +104,10 @@ public:
   }
   SourceMediaStream *GetSourceStream()
   {
-    MOZ_ASSERT(mStream);
+    NS_ASSERTION(mStream,"Getting stream from never-activated GUMCMSListener");
+    if (!mStream) {
+      return nullptr;
+    }
     return mStream->AsSourceStream();
   }
 
@@ -202,9 +205,8 @@ public:
     SourceMediaStream *source = mListener->GetSourceStream();
     // No locking between these is required as all the callbacks for the
     // same MediaStream will occur on the same thread.
-    MOZ_ASSERT(source);
-    if (!source)  // paranoia
-      return NS_ERROR_FAILURE;
+    if (!source) // means the stream was never Activated()
+      return NS_OK;
 
     switch (mType) {
       case MEDIA_START: