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

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

 // 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.
 
 cr.define('settings_search_engines_page', function() {
   /**
    * @param {boolean} canBeDefault
    * @param {boolean} canBeEdited
    * @param {boolean} canBeRemoved
    * @return {!SearchEngine}
@@ skipping 323 matching lines @@
   }
 
   function registerOmniboxExtensionEntryTests() {
     suite('OmniboxExtensionEntryTests', function() {
       /** @type {?SettingsOmniboxExtensionEntryElement} */
       var entry = null;
 
       var browserProxy = null;
 
       setup(function() {
-        browserProxy = new settings_search.TestSearchEnginesBrowserProxy();
-        settings.SearchEnginesBrowserProxyImpl.instance_ = browserProxy;
+        browserProxy = new TestExtensionControlBrowserProxy();
+        settings.ExtensionControlBrowserProxyImpl.instance_ = browserProxy;
         PolymerTest.clearBody();
         entry = document.createElement('settings-omnibox-extension-entry');
         entry.set('engine', createSampleOmniboxExtension());
         document.body.appendChild(entry);
 
         // Open action menu.
         MockInteractions.tap(entry.$$('paper-icon-button'));
       });
 
       teardown(function() { entry.remove(); });
@@ skipping 22 matching lines @@
 
   return {
     registerTests: function() {
       registerDialogTests();
       registerSearchEngineEntryTests();
       registerOmniboxExtensionEntryTests();
       registerPageTests();
     },
   };
 });