MD Settings: implement support for extension-controlled startup URLs

chrome/browser/resources/settings/controls/compiled_resources2.gyp

 # Copyright 2016 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': 'controlled_button',
       'dependencies': [
         '<(DEPTH)/ui/webui/resources/cr_elements/policy/compiled_resources2.gyp:cr_policy_pref_behavior',
         '<(DEPTH)/ui/webui/resources/js/compiled_resources2.gyp:assert',
         'pref_control_behavior',
       ],
       'includes': ['../../../../../third_party/closure_compiler/compile_js2.gypi'],
     },
     {
       'target_name': 'controlled_radio_button',
       'dependencies': [
         '<(DEPTH)/ui/webui/resources/cr_elements/policy/compiled_resources2.gyp:cr_policy_pref_behavior',
         '<(DEPTH)/ui/webui/resources/js/compiled_resources2.gyp:assert',
+        '<(EXTERNS_GYP):settings_private',
         '../prefs/compiled_resources2.gyp:pref_util',
         'pref_control_behavior',
       ],
       'includes': ['../../../../../third_party/closure_compiler/compile_js2.gypi'],
     },
     {
       'target_name': 'extension_controlled_indicator',
       'dependencies': [
         '<(DEPTH)/ui/webui/resources/js/compiled_resources2.gyp:assert',
         '<(DEPTH)/ui/webui/resources/js/compiled_resources2.gyp:i18n_behavior',
@@ skipping 63 matching lines @@
     },
     {
       'target_name': 'settings_toggle_button',
       'dependencies': [
         'settings_boolean_control_behavior',
       ],
       'includes': ['../../../../../third_party/closure_compiler/compile_js2.gypi'],
     },
   ],
 }