Reduce GPU mailbox size to 16 bytes

gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h

 // Copyright 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 is auto-generated from
 // gpu/command_buffer/build_gles2_cmd_buffer.py
 // It's formatted by clang-format using chromium coding style:
 //    clang-format -i -style=chromium filename
 // DO NOT EDIT!
 
@@ skipping 3436 matching lines @@
     {
         0x9500, "GL_PERFQUERY_GPA_EXTENDED_COUNTERS_INTEL",
     },
     {
         0xFFFFFFFF, "GL_ALL_SHADER_BITS_EXT",
     },
     {
         1, "GL_ES_VERSION_2_0",
     },
     {
+        16, "GL_MAILBOX_SIZE_CHROMIUM",
+    },
+    {
         24, "GL_SYNC_TOKEN_SIZE_CHROMIUM",
     },
-    {
-        64, "GL_MAILBOX_SIZE_CHROMIUM",
-    },
 };
 
 const GLES2Util::EnumToString* const GLES2Util::enum_to_string_table_ =
     enum_to_string_table;
 const size_t GLES2Util::enum_to_string_table_len_ =
     sizeof(enum_to_string_table) / sizeof(enum_to_string_table[0]);
 
 std::string GLES2Util::GetStringAttachment(uint32_t value) {
   static const EnumToString string_table[] = {
       {GL_COLOR_ATTACHMENT0, "GL_COLOR_ATTACHMENT0"},
@@ skipping 1517 matching lines @@
 
 std::string GLES2Util::GetStringVertexPointer(uint32_t value) {
   static const EnumToString string_table[] = {
       {GL_VERTEX_ATTRIB_ARRAY_POINTER, "GL_VERTEX_ATTRIB_ARRAY_POINTER"},
   };
   return GLES2Util::GetQualifiedEnumString(string_table,
                                            arraysize(string_table), value);
 }
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_UTILS_IMPLEMENTATION_AUTOGEN_H_