MD Settings: create a shared handler/browser proxy to control extensions

chrome/test/data/webui/settings/cr_settings_browsertest.js

 // 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.
 
 /** @fileoverview Runs the Polymer Settings tests. */
 
 /** @const {string} Path to source root. */
 var ROOT_PATH = '../../../../../';
 
 // Polymer BrowserTest fixture.
@@ skipping 525 matching lines @@
 CrSettingsSearchEnginesTest.prototype = {
   __proto__: CrSettingsBrowserTest.prototype,
 
   /** @override */
   browsePreload:
       'chrome://md-settings/search_engines_page/search_engines_page.html',
 
   /** @override */
   extraLibraries: CrSettingsBrowserTest.prototype.extraLibraries.concat([
     'test_browser_proxy.js',
+    'test_extension_control_browser_proxy.js',
     'test_search_engines_browser_proxy.js',
     'search_engines_page_test.js',
   ]),
 };
 
 TEST_F('CrSettingsSearchEnginesTest', 'SearchEngines', function() {
   settings_search_engines_page.registerTests();
   mocha.run();
 });
 
@@ skipping 491 matching lines @@
   extraLibraries: CrSettingsBrowserTest.prototype.extraLibraries.concat([
     'date_time_page_tests.js',
   ]),
 };
 
 TEST_F('CrSettingsDateTimePageTest', 'DateTimePageTest', function() {
   mocha.run();
 });
 
 GEN('#endif');