[NOT FOR REVIEW][PPAPI] Implement MediaStreamVideoTrack pepper API

ppapi/api/ppb_media_stream_video_track.idl

 /* 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.
  */
 
 /**
  * Defines the <code>PPB_MediaStreamVideoTrack</code> interface. Used for
  * receiving video frames from a MediaStream video track in the browser.
  * This interface is still in development (Dev API status) and may change.
  */
@@ skipping 59 matching lines @@
   /**
    * Gets the next video frame from the MediaStream track.
    * If internal processing is slower than the incoming frame rate, new frames
    * will be dropped from the incoming stream. Once the input buffer is full,
    * frames will be dropped until <code>RecycleFrame()</code> is called to free
    * a spot for another frame to be buffered.
    * If there are no frames in the input buffer,
    * <code>PP_OK_COMPLETIONPENDING</code> will be returned immediately and the
    * <code>callback</code> will be called, when a new frame is received or an
    * error happens.
-   * If the caller holds a frame returned by the previous call of
-   * <code>GetFrame()</code>, <code>PP_ERROR_INPROGRESS</code> will be returned.
-   * The caller should recycle the previous frame before getting the next frame.
    *
    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
    * resource.
    * @param[out] frame A <code>PP_Resource</code> corresponding to a VideoFrame
    * resource.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
    * completion of GetFrame().
    *
    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
    * Returns PP_ERROR_NOMEMORY if <code>max_buffered_frames</code> frames buffer
@@ skipping 22 matching lines @@
   /**
    * Closes the MediaStream video track and disconnects it from video source.
    * After calling <code>Close()</code>, no new frames will be received.
    *
    * @param[in] video_track A <code>PP_Resource</code> corresponding to a
    * MediaStream video track resource.
    */
   void Close([in] PP_Resource video_track);
 };