Remove connection from AudioParamHandler to AudioContext.

third_party/WebKit/Source/modules/webaudio/AudioParam.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
@@ skipping 43 matching lines @@
 public:
     static const double DefaultSmoothingConstant;
     static const double SnapThreshold;
 
     static PassRefPtr<AudioParamHandler> create(AbstractAudioContext& context, double defaultValue)
     {
         return adoptRef(new AudioParamHandler(context, defaultValue));
     }
 
     // This should be used only in audio rendering thread.
-    AbstractAudioContext* context() const;
+    AudioDestinationHandler& destinationHandler() const;
 
     // AudioSummingJunction
     void didUpdate() override { }
 
     AudioParamTimeline& timeline() { return m_timeline; }
 
     // Intrinsic value.
     float value();
     void setValue(float);
 
@@ skipping 25 matching lines @@
     void connect(AudioNodeOutput&);
     void disconnect(AudioNodeOutput&);
 
     float intrinsicValue() const { return noBarrierLoad(&m_intrinsicValue); }
 private:
     AudioParamHandler(AbstractAudioContext& context, double defaultValue)
         : AudioSummingJunction(context.deferredTaskHandler())
         , m_intrinsicValue(defaultValue)
         , m_defaultValue(defaultValue)
         , m_smoothedValue(defaultValue)
-        , m_context(&context) { }
+        , m_destinationHandler(context.destination()->audioDestinationHandler())
+    { }
 
     // sampleAccurate corresponds to a-rate (audio rate) vs. k-rate in the Web Audio specification.
     void calculateFinalValues(float* values, unsigned numberOfValues, bool sampleAccurate);
     void calculateTimelineValues(float* values, unsigned numberOfValues);
 
     // Intrinsic value
     float m_intrinsicValue;
     void setIntrinsicValue(float newValue) { noBarrierStore(&m_intrinsicValue, newValue); }
 
     float m_defaultValue;
 
     // Smoothing (de-zippering)
     float m_smoothedValue;
 
     AudioParamTimeline m_timeline;
 
-    // We can't make this Persistent because of a reference cycle. It's safe to
-    // access this field only when we're rendering audio.
-    UntracedMember<AbstractAudioContext> m_context;
+    // The destination node used to get necessary information like the smaple rate and context time.
+    RefPtr<AudioDestinationHandler> m_destinationHandler;
 };
 
 // AudioParam class represents web-exposed AudioParam interface.
 class AudioParam final : public GarbageCollectedFinalized<AudioParam>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static AudioParam* create(AbstractAudioContext&, double defaultValue);
     DECLARE_TRACE();
     // |handler| always returns a valid object.
     AudioParamHandler& handler() const { return *m_handler; }
@@ skipping 13 matching lines @@
 private:
     AudioParam(AbstractAudioContext&, double defaultValue);
 
     RefPtr<AudioParamHandler> m_handler;
     Member<AbstractAudioContext> m_context;
 };
 
 } // namespace blink
 
 #endif // AudioParam_h