PPAPI: Make blocking completion callbacks work.

ppapi/shared_impl/ppb_video_decoder_shared.h

Index: ppapi/shared_impl/ppb_video_decoder_shared.h
diff --git a/ppapi/shared_impl/ppb_video_decoder_shared.h b/ppapi/shared_impl/ppb_video_decoder_shared.h
index 9f1aa46fcebb16aec298ab1740bab2eb3ef94207..6f62041ac3290fb3609dbdb51cae1dc36735dd1a 100644
--- a/ppapi/shared_impl/ppb_video_decoder_shared.h
+++ b/ppapi/shared_impl/ppb_video_decoder_shared.h
@@ -40,10 +40,10 @@ class PPAPI_SHARED_EXPORT PPB_VideoDecoder_Shared
   virtual void Destroy() OVERRIDE;
 
  protected:
-  bool SetFlushCallback(PP_CompletionCallback callback);
-  bool SetResetCallback(PP_CompletionCallback callback);
-  bool SetBitstreamBufferCallback(
-      int32 bitstream_buffer_id, PP_CompletionCallback callback);
+  bool SetFlushCallback(ApiCallbackType callback);
+  bool SetResetCallback(ApiCallbackType callback);
+  bool SetBitstreamBufferCallback(int32 bitstream_buffer_id,
+                                  ApiCallbackType callback);
 
   void RunFlushCallback(int32 result);
   void RunResetCallback(int32 result);