Handle loops in audio graph better for PannerNodes

Source/modules/webaudio/PannerNode.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 15 matching lines @@
 #define PannerNode_h
 
 #include "platform/audio/AudioBus.h"
 #include "platform/audio/Cone.h"
 #include "platform/audio/Distance.h"
 #include "platform/audio/Panner.h"
 #include "modules/webaudio/AudioListener.h"
 #include "modules/webaudio/AudioNode.h"
 #include "modules/webaudio/AudioParam.h"
 #include "platform/geometry/FloatPoint3D.h"
+#include "wtf/HashMap.h"
 #include "wtf/OwnPtr.h"
 
 namespace WebCore {
 
 // PannerNode is an AudioNode with one input and one output.
 // It positions a sound in 3D space, with the exact effect dependent on the panning model.
 // It has a position and an orientation in 3D space which is relative to the position and orientation of the context's AudioListener.
 // A distance effect will attenuate the gain as the position moves away from the listener.
 // A cone effect will attenuate the gain as the orientation moves away from the listener.
 // All of these effects follow the OpenAL specification very closely.
@@ skipping 84 matching lines @@
     virtual double latencyTime() const OVERRIDE { return m_panner ? m_panner->latencyTime() : 0; }
 
 private:
     PannerNode(AudioContext*, float sampleRate);
 
     // Returns the combined distance and cone gain attenuation.
     float distanceConeGain();
 
     // Notifies any AudioBufferSourceNodes connected to us either directly or indirectly about our existence.
     // This is in order to handle the pitch change necessary for the doppler shift.
-    void notifyAudioSourcesConnectedToNode(AudioNode*);
+    void notifyAudioSourcesConnectedToNode(AudioNode*, HashMap<AudioNode*, bool> &visitedNodes);
 
     OwnPtr<Panner> m_panner;
     unsigned m_panningModel;
 
     FloatPoint3D m_position;
     FloatPoint3D m_orientation;
     FloatPoint3D m_velocity;
 
     // Gain
     RefPtr<AudioParam> m_distanceGain;
     RefPtr<AudioParam> m_coneGain;
     DistanceEffect m_distanceEffect;
     ConeEffect m_coneEffect;
     float m_lastGain;
 
     unsigned m_connectionCount;
 
     // Synchronize process() and setPanningModel() which can change the panner.
     mutable Mutex m_pannerLock;
 };
 
 } // namespace WebCore
 
 #endif // PannerNode_h