[Extern Generation] Add a presubmit script to check externs not being updated

chrome/browser/resources/options/compiled_resources.gyp

 # 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.
 {
   'targets': [
     {
       'target_name': 'options_bundle',
       'variables': {
         'depends': [
           '../../../../third_party/jstemplate/compiled_resources.gyp:jstemplate',
@@ skipping 28 matching lines @@
           '../../../../ui/webui/resources/js/event_tracker.js',
           '../../../../ui/webui/resources/js/load_time_data.js',
           '../../../../ui/webui/resources/js/parse_html_subset.js',
           '../../../../ui/webui/resources/js/util.js',
           '../../../../chrome/browser/resources/chromeos/keyboard/keyboard_utils.js',
         ],
         # options_bundle is included as a complex dependency. Currently there is
         # no possibility to use gyp variable expansion to it, so we don't use
         # <(CLOSURE_DIR) in the "externs" line.
         'externs': [
-          '../../../../third_party/closure_compiler/externs/bluetooth.js',
           '../../../../third_party/closure_compiler/externs/bluetooth_private.js',
           '../../../../third_party/closure_compiler/externs/management.js',
           '../../../../third_party/closure_compiler/externs/metrics_private.js',
           '../../../../third_party/closure_compiler/externs/networking_private.js',
           '../../../../third_party/closure_compiler/externs/chrome_send.js',
+          '../../../../ui/externs/bluetooth.js',
           '../../../../ui/webui/resources/cr_elements/network/cr_network_icon_externs.js',
         ],
       },
       'includes': ['../../../../third_party/closure_compiler/compile_js.gypi'],
     }
   ],
 }