Support multichannel audio stream more than 2 in MediaStreamDestinationNode

third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.h

 /*
  * Copyright (C) 2012, 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 28 matching lines @@
 
 class MediaStreamAudioDestinationHandler final : public AudioBasicInspectorHandler {
 public:
     static PassRefPtr<MediaStreamAudioDestinationHandler> create(AudioNode&, size_t numberOfChannels);
     ~MediaStreamAudioDestinationHandler() override;
 
     MediaStream* stream() { return m_stream.get(); }
 
     // AudioHandler.
     void process(size_t framesToProcess) override;
+    void setChannelCount(unsigned long, ExceptionState&) override;
+
+    unsigned long maxChannelCount() const;
 
 private:
     MediaStreamAudioDestinationHandler(AudioNode&, size_t numberOfChannels);
     // As an audio source, we will never propagate silence.
     bool propagatesSilence() const override { return false; }
 
     // This Persistent doesn't make a reference cycle.
     Persistent<MediaStream> m_stream;
     Persistent<MediaStreamSource> m_source;
+
+    // This internal mix bus is for up/down mixing the input to the actual
+    // number of channels in the destination.
     RefPtr<AudioBus> m_mixBus;
 };
 
 class MediaStreamAudioDestinationNode final : public AudioBasicInspectorNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static MediaStreamAudioDestinationNode* create(AbstractAudioContext&, size_t numberOfChannels);
     MediaStream* stream() const;
 
 private:
     MediaStreamAudioDestinationNode(AbstractAudioContext&, size_t numberOfChannels);
 };
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)
 
 #endif // MediaStreamAudioDestinationNode_h