[PPAPI] Pepper MediaStream API audio track implementation and example.

ppapi/thunk/ppb_audio_frame_api.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_THUNK_PPB_AUDIO_FRAME_API_H_
 #define PPAPI_THUNK_PPB_AUDIO_FRAME_API_H_
 
 #include "ppapi/c/ppb_audio_frame.h"
 #include "ppapi/thunk/ppapi_thunk_export.h"
 
 namespace ppapi {
+
+union MediaStreamFrame;
+
 namespace thunk {
 
 class PPAPI_THUNK_EXPORT PPB_AudioFrame_API {
  public:
   virtual ~PPB_AudioFrame_API() {}
   virtual PP_TimeDelta GetTimestamp() = 0;
   virtual void SetTimestamp(PP_TimeDelta timestamp) = 0;
+  virtual PP_AudioFrame_SampleRate GetSampleRate() = 0;
   virtual PP_AudioFrame_SampleSize GetSampleSize() = 0;
   virtual uint32_t GetNumberOfChannels() = 0;
   virtual uint32_t GetNumberOfSamples() = 0;
   virtual void* GetDataBuffer() = 0;
   virtual uint32_t GetDataBufferSize() = 0;
+
+  // Methods used by Pepper internal implementation only.
+  virtual MediaStreamFrame* GetFrameBuffer() = 0;
+  virtual int32_t GetFrameBufferIndex() = 0;
+  virtual void Invalidate() = 0;
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif  // PPAPI_THUNK_PPB_AUDIO_FRAME_API_H_