Fix AudioNode.disconnect() to support selective disconnection.

Source/modules/webaudio/AudioNodeOutput.h

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 48 matching lines @@
     // Called from context's audio thread.
     AudioBus* bus() const;
 
     // renderingFanOutCount() is the number of AudioNodeInputs that we're connected to during rendering.
     // Unlike fanOutCount() it will not change during the course of a render quantum.
     unsigned renderingFanOutCount() const;
 
     // Must be called with the context's graph lock.
     void disconnectAll();
 
+    // Disconnect a specific input or AudioParam.
+    void disconnectInput(AudioNodeInput &);
+    void disconnectAudioParam(AudioParam &);
+
     void setNumberOfChannels(unsigned);
     unsigned numberOfChannels() const { return m_numberOfChannels; }
     bool isChannelCountKnown() const { return numberOfChannels() > 0; }
 
     bool isConnected() { return fanOutCount() > 0 || paramFanOutCount() > 0; }
 
+    // Probe if the output node is connected with a certain input or AudioParam
+    bool isConnectedToInput(AudioNodeInput &);
+    bool isConnectedToAudioParam(AudioParam &);
+
     // Disable/Enable happens when there are still JavaScript references to a node, but it has otherwise "finished" its work.
     // For example, when a note has finished playing.  It is kept around, because it may be played again at a later time.
     // They must be called with the context's graph lock.
     void disable();
     void enable();
 
     // updateRenderingState() is called in the audio thread at the start or end of the render quantum to handle any recent changes to the graph state.
     // It must be called with the context's graph lock.
     void updateRenderingState();
 
@@ skipping 64 matching lines @@
     // These value should only be changed at the very start or end of the rendering quantum.
     unsigned m_renderingFanOutCount;
     unsigned m_renderingParamFanOutCount;
 
     HeapHashSet<Member<AudioParam>> m_params;
 };
 
 } // namespace blink
 
 #endif // AudioNodeOutput_h