Update PPB_VideoDecoder documentation.

ppapi/api/ppb_video_decoder.idl

 /* Copyright (c) 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.
  */
 
 /**
  * This file defines the <code>PPB_VideoDecoder</code> interface.
  */
 
 [generate_thunk]
@@ skipping 73 matching lines @@
    */
   int32_t Initialize(
       [in] PP_Resource video_decoder,
       [in] PP_Resource graphics3d_context,
       [in] PP_VideoProfile profile,
       [in] PP_Bool allow_software_fallback,
       [in] PP_CompletionCallback callback);
 
   /**
    * Decodes a bitstream buffer. Copies |size| bytes of data from the plugin's
-   * |buffer|. The plugin should maintain the buffer and not call Decode() again
-   * until the decoder signals completion by returning PP_OK or by running
-   * |callback|.
+   * |buffer|. The plugin should wait until the decoder signals completion by
+   * returning PP_OK or by running |callback| before calling Decode() again.

[dmichael (off chromium), 2014/05/20 19:47:32]

May be worth noting that otherwise it will fail with PP_ERROR_INPROGRESS

[bbudge, 2014/05/20 21:04:57]

Documented this in the @return section.

    *
    * In general, each bitstream buffer should contain a demuxed bitstream frame
    * for the selected video codec. For example, H264 decoders expect to receive
    * one AnnexB NAL unit, including the 4 byte start code prefix, while VP8
    * decoders expect to receive a bitstream frame without the IVF frame header.
    *
    * If the call to Decode() eventually results in a picture, the |decode_id|
    * parameter is copied into the returned picture. The plugin can use this to
    * associate decoded pictures with Decode() calls (e.g. to assign timestamps
    * or frame numbers to pictures.) This value is opaque to the API so the
@@ skipping 87 matching lines @@
    * decoder.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called on
    * completion.
    *
    * @return An int32_t containing an error code from <code>pp_errors.h</code>.
    */
   int32_t Reset(
       [in] PP_Resource video_decoder,
       [in] PP_CompletionCallback callback);
 };