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

gpu/ipc/BUILD.gn

 # 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.
 
 group("ipc") {
   if (is_component_build) {
     public_deps = [
       "//gpu",
     ]
   } else {
     public_deps = [
       ":ipc_sources",
     ]
   }
 }
 
 source_set("ipc_sources") {
   visibility = [ "//gpu/*" ]
 
   sources = [
     "gpu_command_buffer_traits.cc",
     "gpu_command_buffer_traits.h",
+    "id_type_traits.h",
   ]
 
   configs += [
     "//gpu:gpu_implementation",
     "//third_party/khronos:khronos_headers",
   ]
 
   deps = [
     "//gpu/command_buffer/common:common_sources",
     "//ipc",
   ]
 }