MD Settings: show an extension-controlled-indicator for proxy

chrome/browser/resources/settings/settings_ui/settings_ui.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
  * 'settings-ui' implements the UI for the Settings page.
  *
  * Example:
  *
@@ skipping 125 matching lines @@
     // sync the URL parameter to the textbox.
     if (urlSearchQuery != searchField.getValue()) {
       // Setting the search box value without triggering a 'search-changed'
       // event, to prevent an unnecessary duplicate entry in |window.history|.
       searchField.setValue(urlSearchQuery, true /* noEvent */);
     }
 
     this.$.main.searchContents(urlSearchQuery);
   },
 
+  /** @return {SettingsPrefsElement} */
+  getPrefsElement: function() {
+    return this.$.prefs;
+  },
+
   /**
    * Handles the 'search-changed' event fired from the toolbar.
    * @param {!Event} e
    * @private
    */
   onSearchChanged_: function(e) {
     // Trim leading whitespace only, to prevent searching for empty string. This
     // still allows the user to search for 'foo bar', while taking a long pause
     // after typing 'foo '.
     var query = e.detail.replace(/^\s+/, '');
@@ skipping 20 matching lines @@
   onMenuButtonTap_: function() {
     this.$$('app-drawer').toggle();
   },
 
   /** @private */
   directionDelegateChanged_: function() {
     this.$$('app-drawer').align = this.directionDelegate.isRtl() ?
         'right' : 'left';
   },
 });