Make reduction value of dynamics compressor zero when no sources are connected

Source/modules/webaudio/AudioNode.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 102 matching lines @@
     // The AudioNodeInput(s) (if any) will already have their input data available when process() is called.
     // Subclasses will take this input data and put the results in the AudioBus(s) of its AudioNodeOutput(s) (if any).
     // Called from context's audio thread.
     virtual void process(size_t framesToProcess) = 0;
 
     // No significant resources should be allocated until initialize() is called.
     // Processing may not occur until a node is initialized.
     virtual void initialize();
     virtual void uninitialize();
 
+    // Clear internal state when the node is disabled.  When a node is disabled,
+    // it is no longer pulled so any internal state is never updated. But some
+    // nodes (DynamicsCompressorNode) have internal state that is still
+    // accessible by the user.  Update the internal state as if the node were
+    // still connected but processing all zeroes. This gives a consistent view
+    // to the user.

[Raymond Toy, 2014/10/21 23:25:51]

Nit: I think blink style is to use one space after a period. (I have a long
habit of using two.) This is no longer enforced but you're supposed to use a
style consistent with the file.

[hongchan, 2014/10/21 23:43:21]

Acknowledged.

+    virtual void clearInternalStateWhenDisabled();
+
     bool isInitialized() const { return m_isInitialized; }
 
     unsigned numberOfInputs() const { return m_inputs.size(); }
     unsigned numberOfOutputs() const { return m_outputs.size(); }
 
     AudioNodeInput* input(unsigned);
     AudioNodeOutput* output(unsigned);
 
     // Called from main thread by corresponding JavaScript methods.
     virtual void connect(AudioNode*, unsigned outputIndex, unsigned inputIndex, ExceptionState&);
@@ skipping 93 matching lines @@
     ChannelCountMode m_channelCountMode;
     AudioBus::ChannelInterpretation m_channelInterpretation;
     // The new channel count mode that will be used to set the actual mode in the pre or post
     // rendering phase.
     ChannelCountMode m_newChannelCountMode;
 };
 
 } // namespace blink
 
 #endif // AudioNode_h