Introducing gpu::CommandBufferId as a distinct, IdType<...>-based type.

gpu/command_buffer/common/command_buffer_id.h

Index: gpu/command_buffer/common/command_buffer_id.h
diff --git a/gpu/command_buffer/common/command_buffer_id.h b/gpu/command_buffer/common/command_buffer_id.h
new file mode 100644
index 0000000000000000000000000000000000000000..99b5bb8621a99c1e9c19db57c1f79932705259aa
--- /dev/null
+++ b/gpu/command_buffer/common/command_buffer_id.h
@@ -0,0 +1,17 @@
+// Copyright 2015 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_COMMAND_BUFFER_ID_H_
+#define GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_ID_H_
+
+#include "gpu/command_buffer/common/id_type.h"
+
+namespace gpu {
+
+class CommandBuffer;
+using CommandBufferId = gpu::IdTypeU64<CommandBuffer>;
+
+}  // namespace gpu
+
+#endif  // GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_ID_H_