Rename PPAPI Video Stream APIs.

ppapi/api/private/pp_video_frame_private.idl

 /* Copyright (c) 2013 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.
  */
 
 /**
  * This file defines the struct used to hold a video frame.
  */
 
 /**
- * The <code>PP_Video_Frame</code> struct represents a video frame.
+ * The <code>PP_VideoFrame_Private</code> struct represents a video frame.
+ * Video sources and destinations use frames to transfer video to and from
+ * the browser.
  */
 [assert_size(16)]
-struct PP_VideoFrame {
+struct PP_VideoFrame_Private {
   /**
    * A timestamp placing the frame in a video stream.
    */
   PP_TimeTicks timestamp;
 
   /**
    * An image data resource to hold the video frame.
    */
   PP_Resource image_data;
 
   /**
    * Ensure that this struct is 16-bytes wide by padding the end.  In some
    * compilers, PP_TimeTicks is 8-byte aligned, so those compilers align this
    * struct on 8-byte boundaries as well and pad it to 8 bytes even without this
    * padding attribute.  This padding makes its size consistent across
    * compilers.
    */
   int32_t padding;
 };