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

ppapi/shared_impl/media_stream_frame.h

Index: ppapi/shared_impl/media_stream_frame.h
diff --git a/ppapi/shared_impl/media_stream_frame.h b/ppapi/shared_impl/media_stream_frame.h
index b3ec8bb213f93fbcef2c0323367ac5968f8282ba..72eeef937040d2013e9a18ab109a0ebb940ad127 100644
--- a/ppapi/shared_impl/media_stream_frame.h
+++ b/ppapi/shared_impl/media_stream_frame.h
@@ -5,6 +5,7 @@
 #ifndef PPAPI_SHARED_IMPL_MEDIA_STREAM_FRAME_H_
 #define PPAPI_SHARED_IMPL_MEDIA_STREAM_FRAME_H_
 
+#include "ppapi/c/ppb_audio_frame.h"
 #include "ppapi/c/ppb_video_frame.h"
 
 namespace ppapi {
@@ -23,7 +24,14 @@ union MediaStreamFrame {
 
   struct Audio {
     Header header;
-    // TODO(penghuang): implement the audio frame.
+    PP_TimeDelta timestamp;
+    PP_AudioFrame_SampleRate sample_rate;
+    uint32_t number_of_channels;
+    uint32_t number_of_samples;
+    uint32_t data_size;
+    // Uses 8 bytes to make sure the Audio struct has consistent size between
+    // NaCl code and renderer code.
+    uint8_t data[8];
   };
 
   struct Video {
@@ -33,7 +41,7 @@ union MediaStreamFrame {
     PP_Size size;
     uint32_t data_size;
     // Uses 8 bytes to make sure the Video struct has consistent size between
-    // Nacl code and renderer code.
+    // NaCl code and renderer code.
     uint8_t data[8];
   };
 
@@ -41,7 +49,7 @@ union MediaStreamFrame {
   // the size and alighment to be consistent between NaCl and its host trusted
   // platform.
   PP_COMPILE_ASSERT_SIZE_IN_BYTES(Header, 8);
-  PP_COMPILE_ASSERT_SIZE_IN_BYTES(Audio, 8);
+  PP_COMPILE_ASSERT_SIZE_IN_BYTES(Audio, 40);
   PP_COMPILE_ASSERT_SIZE_IN_BYTES(Video, 40);
 
   Header header;