Move services code brought in from Mojo to live under //third_party.

mojo/services/public/build/config/BUILD.gn

-# Copyright 2014 The Chromium Authors. All rights reserved.
+# 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.
 
-# The absolute path to the directory containing the Mojo services.
+# The absolute path to the directory containing the Mojo services produced
+# out of Chromium.
 mojo_services_root = get_path_info("../../..", "abspath")
 
+# NOTE: This config name must be in sync with the name of the config used by
+# services that developed out of the Mojo repo so that Chromium's services'
+# BUILD.gn files can work seamlessly in Chromium and when pulled into Mojo or a
+# client repo.
 config("mojo_services") {
   include_dirs = [
-    # Include paths in Mojo services' client-side code are specified relative
-    # to the directory holding the services' client-side code.
+    # Include paths in Chromium Mojo services' client-side code are specified
+    # relative to the directory holding the services' client-side code.
     mojo_services_root,
 
     # The same goes for files generated from mojoms.
     root_gen_dir + mojo_services_root,
   ]
 }