Change the way audio mixer gets "pending bytes" (amount of data currently buffered

media/audio/audio_output_mixer.h

Index: media/audio/audio_output_mixer.h
===================================================================
--- media/audio/audio_output_mixer.h	(revision 133745)
+++ media/audio/audio_output_mixer.h	(working copy)
@@ -10,6 +10,7 @@
 #define MEDIA_AUDIO_AUDIO_OUTPUT_MIXER_H_
 
 #include <map>
+#include <set>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
@@ -61,6 +62,14 @@
   // audio manager thread is safe.
   base::Lock lock_;
 
+  // Information for each each in-flight buffer.
+  struct BufferData {
+    explicit BufferData(int len) : length(len) { }
+    int length;
+  };
+  typedef std::map<void*, BufferData> BufferMap;
+  BufferMap buffer_data_;
+
   // List of audio output proxies currently being played.
   // For every proxy we store aux structure containing data necessary for
   // mixing.
@@ -68,6 +77,9 @@
     AudioOutputStream::AudioSourceCallback* audio_source_callback;
     double volume;
     int pending_bytes;
+    std::set<void*> buffers;  // Used to catch when we stop prebuffering and
+                              // start releasing buffers.
+    bool prebuffering;
   };
   typedef std::map<AudioOutputProxy*, ProxyData> ProxyMap;
   ProxyMap proxies_;