Support configuring the audio buffer duration in the Pepper MediaStream API.

ppapi/shared_impl/media_stream_audio_track_shared.h

 // Copyright 2014 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 PPAPI_SHARED_IMPL_MEDIA_STREAM_AUDIO_TRACK_SHARED_H_
 #define PPAPI_SHARED_IMPL_MEDIA_STREAM_AUDIO_TRACK_SHARED_H_
 
 #include "ppapi/c/ppb_audio_buffer.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 
 namespace ppapi {
 
 class PPAPI_SHARED_EXPORT MediaStreamAudioTrackShared {
  public:
   struct Attributes {
-    Attributes() : buffers(0) {}
+    Attributes() : buffers(0), duration(0) {}
     int32_t buffers;
+    int32_t duration;
   };
 
   static bool VerifyAttributes(const Attributes& attributes);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_MEDIA_STREAM_AUDIO_TRACK_SHARED_H_