Bug 1195185. Part 2 - Check if all output streams are from the same graph because we don't support connecting streams from different graphs. r=roc.

dom/media/DecodedStream.cpp

@@ -293,10 +293,19 @@ OutputStreamData::Remove()
   mOwner->Remove(mStream);
 }
 
+MediaStreamGraph*
+OutputStreamData::Graph() const
+{
+  return mStream->Graph();
+}
+
 void
 OutputStreamManager::Add(ProcessedMediaStream* aStream, bool aFinishWhenEnded)
 {
   MOZ_ASSERT(NS_IsMainThread());
+  // All streams must belong to the same graph.
+  MOZ_ASSERT(!Graph() || Graph() == aStream->Graph());
+
   // Ensure that aStream finishes the moment mDecodedStream does.
   if (aFinishWhenEnded) {
     aStream->SetAutofinish(true);

dom/media/DecodedStream.h

@@ -56,6 +56,8 @@ public:
   {
     return mStream == aStream;
   }
+  // Return the graph mStream belongs to.
+  MediaStreamGraph* Graph() const;
 
 private:
   OutputStreamManager* mOwner;
@@ -81,6 +83,12 @@ public:
   void Connect(MediaStream* aStream);
   // Disconnect all output streams from the input stream.
   void Disconnect();
+  // Return the graph these streams belong to or null if empty.
+  MediaStreamGraph* Graph() const
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    return !IsEmpty() ? mStreams[0].Graph() : nullptr;
+  }
 
 private:
   // Keep the input stream so we can connect the output streams that