Enforce non-negative BitstreamBuffer id

ppapi/c/dev/pp_video_dev.h

 /* Copyright (c) 2012 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.
  */
 
 /* From dev/pp_video_dev.idl modified Fri Dec  7 15:33:11 2012. */
 
 #ifndef PPAPI_C_DEV_PP_VIDEO_DEV_H_
 #define PPAPI_C_DEV_PP_VIDEO_DEV_H_
 
@@ skipping 43 matching lines @@
 
 /**
  * @addtogroup Structs
  * @{
  */
 /**
  * The data structure for video bitstream buffer.
  */
 struct PP_VideoBitstreamBuffer_Dev {
   /**
-   * Client-specified identifier for the bitstream buffer.
+   * Client-specified identifier for the bitstream buffer. Valid values are
+   * non-negative.
    */
   int32_t id;
   /**
    * Buffer to hold the bitstream data. Should be allocated using the
    * PPB_Buffer interface for consistent interprocess behaviour.
    */
   PP_Resource data;
   /**
    * Size of the bitstream contained in buffer (in bytes).
    */
   uint32_t size;
 };
 PP_COMPILE_ASSERT_STRUCT_SIZE_IN_BYTES(PP_VideoBitstreamBuffer_Dev, 12);
 
 /**
  * Struct for specifying texture-backed picture data.
  */
 struct PP_PictureBuffer_Dev {
   /**
    * Client-specified id for the picture buffer. By using this value client can
    * keep track of the buffers it has assigned to the video decoder and how they
-   * are passed back to it.
+   * are passed back to it. Valid values are non-negative.
    */
   int32_t id;
   /**
    * Dimensions of the buffer.
    */
   struct PP_Size size;
   /**
    * Texture ID in the given context where picture is stored.
    */
   uint32_t texture_id;
@@ skipping 47 matching lines @@
    */
   PP_VIDEODECODERERROR_PLATFORM_FAILURE = 4
 } PP_VideoDecodeError_Dev;
 PP_COMPILE_ASSERT_SIZE_IN_BYTES(PP_VideoDecodeError_Dev, 4);
 /**
  * @}
  */
 
 #endif  /* PPAPI_C_DEV_PP_VIDEO_DEV_H_ */