Added an extra sync token field for extra command buffer identification.

gpu/command_buffer/common/constants.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.
 
 #ifndef GPU_COMMAND_BUFFER_COMMON_CONSTANTS_H_
 #define GPU_COMMAND_BUFFER_COMMON_CONSTANTS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 49 matching lines @@
 // failure.
 const int32_t kInvalidSharedMemoryId = -1;
 
 // Common Command Buffer shared memory transfer buffer ID.
 const int32_t kCommandBufferSharedMemoryId = 4;
 
 // The size to set for the program cache.
 const size_t kDefaultMaxProgramCacheMemoryBytes = 6 * 1024 * 1024;
 
 // Namespace used to separate various command buffer types.
-enum CommandBufferNamespace {
+enum CommandBufferNamespace : int8_t {
   INVALID = -1,
 
   GPU_IO,
   IN_PROCESS,
   MOJO,
   MOJO_LOCAL,
   OLD_SYNC_POINTS,
 
   NUM_COMMAND_BUFFER_NAMESPACES
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_CONSTANTS_H_