Bug 804387. Part 10: Add a mechanism for ensuring that we don't attempt to allocate an input port if the input node is not hooked up to MSG yet. r=roc

content/media/webaudio/AudioBufferSourceNode.h

@@ -28,6 +28,10 @@ public:
     }
     AudioSourceNode::DestroyMediaStream();
   }
+  virtual bool SupportsMediaStreams() const MOZ_OVERRIDE
+  {
+    return true;
+  }
 
   NS_DECL_ISUPPORTS_INHERITED
   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(AudioBufferSourceNode, AudioSourceNode)

content/media/webaudio/AudioNode.cpp

@@ -165,12 +165,14 @@ AudioNode::Connect(AudioNode& aDestination, uint32_t aOutput,
   input->mInputNode = this;
   input->mInputPort = aInput;
   input->mOutputPort = aOutput;
-  // Connect streams in the MediaStreamGraph
-  MOZ_ASSERT(aDestination.mStream->AsProcessedStream());
-  ProcessedMediaStream* ps =
-    static_cast<ProcessedMediaStream*>(aDestination.mStream.get());
-  input->mStreamPort =
-    ps->AllocateInputPort(mStream, MediaInputPort::FLAG_BLOCK_OUTPUT);
+  if (SupportsMediaStreams() && aDestination.mStream) {
+    // Connect streams in the MediaStreamGraph
+    MOZ_ASSERT(aDestination.mStream->AsProcessedStream());
+    ProcessedMediaStream* ps =
+      static_cast<ProcessedMediaStream*>(aDestination.mStream.get());
+    input->mStreamPort =
+      ps->AllocateInputPort(mStream, MediaInputPort::FLAG_BLOCK_OUTPUT);
+  }
 }
 
 void

content/media/webaudio/AudioNode.h

@@ -60,6 +60,13 @@ public:
     }
   }
 
+  // This method should be overridden to return true in nodes
+  // which support being hooked up to the Media Stream graph.
+  virtual bool SupportsMediaStreams() const
+  {
+    return false;
+  }
+
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_CLASS(AudioNode)