Complete the implementation of up/down-mixing rules for AudioNode

third_party/WebKit/Source/platform/audio/AudioBus.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 133 matching lines @@
     // Makes maximum absolute value == 1.0 (if possible).
     void normalize();
 
     static PassRefPtr<AudioBus> loadPlatformResource(const char* name, float sampleRate);
 
 protected:
     AudioBus() { }
 
     AudioBus(unsigned numberOfChannels, size_t length, bool allocate);
 
-    void speakersCopyFrom(const AudioBus&);
-    void discreteCopyFrom(const AudioBus&);
-    void speakersSumFrom(const AudioBus&);
     void discreteSumFrom(const AudioBus&);
-    void speakersSumFrom5_1_ToMono(const AudioBus&);
+
+    // Up/down-mix by in-place summing upon the existing channel content.
+    // http://webaudio.github.io/web-audio-api/#channel-up-mixing-and-down-mixing
+    void sumFromByUpMixing(const AudioBus&);
+    void sumFromByDownMixing(const AudioBus&);
 
     size_t m_length;
     Vector<OwnPtr<AudioChannel>> m_channels;
     int m_layout;
     float m_busGain;
     OwnPtr<AudioFloatArray> m_dezipperGainValues;
     bool m_isFirstTime;
     float m_sampleRate; // 0.0 if unknown or N/A
 };
 
 } // namespace blink
 
 #endif // AudioBus_h