Added a unique command buffer ID for command buffers.

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 48 matching lines @@
 // Invalid shared memory Id, returned by RegisterSharedMemory in case of
 // 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 {
+  INVALID = -1,
+
+  GPU_IO,
+  IN_PROCESS,
+  MOJO,
+
+  NUM_COMMAND_BUFFER_NAMESPACES
+};
+
+
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_CONSTANTS_H_