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

ppapi/api/ppb_media_stream_video_track.idl

Index: ppapi/api/ppb_media_stream_video_track.idl
diff --git a/ppapi/api/ppb_media_stream_video_track.idl b/ppapi/api/ppb_media_stream_video_track.idl
index 1f331c0596aac00296c4c3d7687b0e9af68842a0..8f30f9ac0e5217f194b6e0fe70b53b9d6d197b57 100644
--- a/ppapi/api/ppb_media_stream_video_track.idl
+++ b/ppapi/api/ppb_media_stream_video_track.idl
@@ -95,6 +95,9 @@ interface PPB_MediaStreamVideoTrack {
    * 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,