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

ppapi/api/ppb_audio_frame.idl

Index: ppapi/api/ppb_audio_frame.idl
diff --git a/ppapi/api/ppb_audio_frame.idl b/ppapi/api/ppb_audio_frame.idl
index b0c14d4df6adc864004a0f54c3b16b9896cf9656..cb434b8f21ac004030a6118457ddbea9172bf650 100644
--- a/ppapi/api/ppb_audio_frame.idl
+++ b/ppapi/api/ppb_audio_frame.idl
@@ -48,6 +48,17 @@ interface PPB_AudioFrame {
   void SetTimestamp([in] PP_Resource frame, [in] PP_TimeDelta timestamp);
 
   /**
+   * Gets the sample rate of the audio frame.
+   *
+   * @param[in] frame A <code>PP_Resource</code> corresponding to an audio frame
+   * resource.
+   *
+   * @return The sample rate of the audio frame.
+   */
+  [on_failure=PP_AUDIOSAMPLERATE_NONE]
+  PP_AudioSampleRate GetSampleRate([in] PP_Resource frame);
+
+  /**
    * Gets the sample size of the audio frame.
    *
    * @param[in] frame A <code>PP_Resource</code> corresponding to an audio frame