Content "gn check" work.

gpu/command_buffer/client/BUILD.gn

 # Copyright (c) 2013 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.
 
 # The files here go into the "gpu" component in a component build (with
 # "command_buffer_client" and "gles2_cmd_helper" just forwarding) and goes into
 # separate static libraries in non-component build. This needs to match the
 # GYP build which was likely an attempt to make larger components to help with
 # loading.
 group("client") {
@@ skipping 22 matching lines @@
 
 component("client_sources_for_ppapi") {
   public_deps = [
     ":client_sources",
     ":gles2_implementation",
     "//gpu/ipc/common:command_buffer_traits",
   ]
 }
 
 source_set("client_sources") {
+  # External code should depend on this via //gpu/client above rather than
+  # depending on this directly or the component build will break.
   visibility = [ "//gpu/*" ]
 
   sources = [
     "cmd_buffer_helper.cc",
     "cmd_buffer_helper.h",
     "fenced_allocator.cc",
     "fenced_allocator.h",
     "gpu_control.h",
     "gpu_memory_buffer_manager.cc",
     "gpu_memory_buffer_manager.h",
@@ skipping 187 matching lines @@
   ]
   deps = [
     ":client",
     ":gles2_implementation_no_check",
     ":gles2_interface",
     "//base",
     "//base/third_party/dynamic_annotations",
     "//gpu/command_buffer/common",
   ]
 }