Tell CoreAudio how to interpret Chrome's channel layout.

media/base/channel_layout.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_CHANNEL_LAYOUT_H_
 #define MEDIA_BASE_CHANNEL_LAYOUT_H_
 
 #include "media/base/media_export.h"
 
 namespace media {
@@ skipping 94 matching lines @@
   // of that.
   CHANNEL_LAYOUT_STEREO_AND_KEYBOARD_MIC = 30,
 
   // Front L, Front R, Side L, Side R, LFE
   CHANNEL_LAYOUT_4_1_QUAD_SIDE = 31,
 
   // Max value, must always equal the largest entry ever logged.
   CHANNEL_LAYOUT_MAX = CHANNEL_LAYOUT_4_1_QUAD_SIDE
 };
 
+// Note: Do not reorder or reassign these values; other code depends on their
+// ordering to operate correctly. E.g., CoreAudio channel layout computations.
 enum Channels {
   LEFT = 0,
   RIGHT,
   CENTER,
   LFE,
   BACK_LEFT,
   BACK_RIGHT,
   LEFT_OF_CENTER,
   RIGHT_OF_CENTER,
   BACK_CENTER,
@@ skipping 13 matching lines @@
 // Given the number of channels, return the best layout,
 // or return CHANNEL_LAYOUT_UNSUPPORTED if there is no good match.
 MEDIA_EXPORT ChannelLayout GuessChannelLayout(int channels);
 
 // Returns a string representation of the channel layout.
 MEDIA_EXPORT const char* ChannelLayoutToString(ChannelLayout layout);
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_CHANNEL_LAYOUT_H_