Add Mac OS X synchronized audio I/O back-end

media/base/audio_bus.h

Index: media/base/audio_bus.h
===================================================================
--- media/base/audio_bus.h	(revision 156920)
+++ media/base/audio_bus.h	(working copy)
@@ -11,6 +11,10 @@
 #include "base/memory/scoped_ptr.h"
 #include "media/base/media_export.h"
 
+#if defined(OS_MACOSX)
+struct AudioBufferList;
+#endif
+
 namespace media {
 class AudioParameters;
 
@@ -25,6 +29,16 @@
   // SSE optimizations.
   enum { kChannelAlignment = 16 };
 
+  AudioBus(int channels, int frames);
+  AudioBus(int channels, int frames, float* data);
+  AudioBus(int frames, const std::vector<float*>& channel_data);
+
+#if defined(OS_MACOSX)
+  AudioBus(int channels, int frames, AudioBufferList* buffer_list);

[scherkus (not reviewing), 2012/09/17 14:51:17]

let's try to close out this issue sooner rather than later -- perhaps using a
resize() method as dale suggests

+#endif
+
+  ~AudioBus();
+
   // Creates a new AudioBus and allocates |channels| of length |frames|.  Uses
   // channels() and frames_per_buffer() from AudioParameters if given.
   static scoped_ptr<AudioBus> Create(int channels, int frames);
@@ -85,12 +99,7 @@
 
  private:
   friend class scoped_ptr<AudioBus>;
-  ~AudioBus();
 
-  AudioBus(int channels, int frames);
-  AudioBus(int channels, int frames, float* data);
-  AudioBus(int frames, const std::vector<float*>& channel_data);
-
   // Helper method for building |channel_data_| from a block of memory.  |data|
   // must be at least BlockSize() bytes in size.
   void BuildChannelData(int channels, int aligned_frame, float* data);