Fix size calcuation in video_decoder_resource.cc

ppapi/proxy/video_decoder_resource.cc

Index: ppapi/proxy/video_decoder_resource.cc
diff --git a/ppapi/proxy/video_decoder_resource.cc b/ppapi/proxy/video_decoder_resource.cc
index 2dbe60e891965d81ad4bcca2cb4ef137c8d54c66..487b3bae29e72fb0483a4cb13ca79fdecd9907f7 100644
--- a/ppapi/proxy/video_decoder_resource.cc
+++ b/ppapi/proxy/video_decoder_resource.cc
@@ -73,7 +73,7 @@ VideoDecoderResource::VideoDecoderResource(Connection connection,
       // just testing |decoder_last_error_|.
       decoder_last_error_(PP_ERROR_FAILED) {
   // Clear the decode_ids_ array.
-  memset(decode_ids_, 0, arraysize(decode_ids_));
+  memset(decode_ids_, 0, sizeof(decode_ids_));
   SendCreate(RENDERER, PpapiHostMsg_VideoDecoder_Create());
 }