MD Settings: Lazy load the contents of the "advanced" settings.

chrome/browser/resources/settings/basic_page/basic_page.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-basic-page' is the settings page containing the actual settings.
  */
 Polymer({
   is: 'settings-basic-page',
@@ skipping 96 matching lines @@
    * @param {string} query The text to search for.
    * @return {!Promise<!settings.SearchResult>} A signal indicating that
    *     searching finished.
    */
   searchContents: function(query) {
     var whenSearchDone = [
       settings.getSearchManager().search(query, assert(this.$$('#basicPage'))),
     ];
 
     if (this.pageVisibility.advancedSettings !== false) {
-      whenSearchDone.push(settings.getSearchManager().search(
-          query, assert(this.$$('#advancedPageTemplate').get())));
+      whenSearchDone.push(this.$$('#advancedPageTemplate').get().then(
+          function(advancedPage) {
+            return settings.getSearchManager().search(query, advancedPage);
+          }));
     }
 
     return Promise.all(whenSearchDone).then(function(requests) {
       // Combine the SearchRequests results to a single SearchResult object.
       return {
         canceled: requests.some(function(r) { return r.canceled; }),
         didFindMatches: requests.every(function(r) {
           return !r.didFindMatches();
         }),
         // All requests correspond to the same user query, so only need to check
@@ skipping 98 matching lines @@
 
   /**
    * @param {boolean} opened Whether the menu is expanded.
    * @return {string} Icon name.
    * @private
    */
   getArrowIcon_: function(opened) {
     return opened ? 'cr:arrow-drop-up' : 'cr:arrow-drop-down';
   },
 });