[PPAPI][MediaStream] Support configure for video input.

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 77 matching lines @@
    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
    * resource.
    * @param[in] attrib_list A list of attribute name-value pairs in which each
    * attribute is immediately followed by the corresponding desired value.
    * The list is terminated by
    * <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE</code>.
    * @param[in] callback <code>PP_CompletionCallback</code> to be called upon
    * completion of <code>Configure()</code>.
    *
    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
+   * Returns <code>PP_ERROR_INPROGRESS</code> if there is a pending call of
+   * <code>Configure()</code> or <code>GetFrame()</code>, or the plugin
+   * holds some frames which are not recycled with <code>RecycleFrame()</code>.
    */
   int32_t Configure([in] PP_Resource video_track,
                     [in] int32_t[] attrib_list,
                     [in] PP_CompletionCallback callback);
 
   /**
    * Gets attribute value for a given attribute name.
    *
    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
    * resource.
@@ skipping 76 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);
 };