Change PPB_VideoWriter Open function to return stream_id as out param.

ppapi/c/ppb_video_writer.h

Index: ppapi/c/ppb_video_writer.h
diff --git a/ppapi/c/ppb_video_writer.h b/ppapi/c/ppb_video_writer.h
index 7f6681adc5dfff82ea4b80181ed672d36d75d5b5..1aaa3acc3ed99b1be6cb9c34f216c78ecc7aa795 100644
--- a/ppapi/c/ppb_video_writer.h
+++ b/ppapi/c/ppb_video_writer.h
@@ -3,7 +3,7 @@
  * found in the LICENSE file.
  */
 
-/* From ppb_video_writer.idl modified Thu Apr  4 13:47:32 2013. */
+/* From ppb_video_writer.idl modified Fri Apr  5 15:46:57 2013. */
 
 #ifndef PPAPI_C_PPB_VIDEO_WRITER_H_
 #define PPAPI_C_PPB_VIDEO_WRITER_H_
@@ -62,8 +62,8 @@ struct PPB_VideoWriter_0_1 {
    *
    * @param[in] writer A <code>PP_Resource</code> corresponding to a video
    * writer resource.
-   * @param[in] stream_id A <code>PP_Var</code> holding a string uniquely
-   * identifying the stream. This string is application defined.
+   * @param[out] stream_id A <code>PP_Var</code> holding a string uniquely
+   * identifying the stream. This string is generated by the host.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
    * completion of Open().
    *
@@ -72,7 +72,7 @@ struct PPB_VideoWriter_0_1 {
    * Returns PP_ERROR_INPROGRESS if the writer has already opened a stream.
    */
   int32_t (*Open)(PP_Resource writer,
-                  struct PP_Var stream_id,
+                  struct PP_Var* stream_id,
                   struct PP_CompletionCallback callback);
   /**
    * Puts a frame of video to the writer's open stream.