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 {
+  kCommandBufferNamespace_Invalid = -1,

[dcheng, 2015/09/17 17:08:18]

Chrome enum naming convention is to NAME_LIKE_THIS.

Also consider just using enum class.

[David Yen, 2015/09/17 17:26:21]

Done.

+
+  kCommandBufferNamespace_GpuIO,
+  kCommandBufferNamespace_InProcess,
+  kCommandBufferNamespace_Mojo,
+
+  NUM_COMMAND_BUFFER_NAMESPACES

[dcheng, 2015/09/17 17:08:18]

Is this actually used for anything?

[David Yen, 2015/09/17 17:26:21]

The background of this patch is that it was moved out of another CL because
erick@ also needed to identify command buffers. The
NUM_COMMAND_BUFFER_NAMESPACES is used to declare an array for each namespace in
that patch:
(https://codereview.chromium.org/1339203002/diff/60001/gpu/command_buffer/serv...)

+};
+
+
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_CONSTANTS_H_