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

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.
 GEN_INCLUDE(
     [ROOT_PATH + 'chrome/test/data/webui/polymer_browser_test_base.js']);
 
 /**
  * Test fixture for Polymer Settings elements.
  * @constructor
  * @extends {PolymerTest}
  */
 function CrSettingsBrowserTest() {}
 
 CrSettingsBrowserTest.prototype = {
   __proto__: PolymerTest.prototype,
 
   /** @override */
   get browsePreload() {
     throw 'this is abstract and should be overriden by subclasses';
   },
 
   /** @override */
-  extraLibraries: PolymerTest.getLibraries(ROOT_PATH),
+  extraLibraries: PolymerTest.getLibraries(ROOT_PATH).concat([
+    'ensure_lazy_loaded.js',
+  ]),
 
   /** @override */
   setUp: function() {
     PolymerTest.prototype.setUp.call(this);
     // We aren't loading the main document.
     this.accessibilityAuditConfig.ignoreSelectors('humanLangMissing', 'html');
 
     // TODO(michaelpg): Re-enable after bringing in fix for
     // https://github.com/PolymerElements/paper-slider/issues/131.
     this.accessibilityAuditConfig.ignoreSelectors(
         'badAriaAttributeValue', 'paper-slider');
+
+    settings.ensureLazyLoaded();
   },
 };
 
 // Have to include command_line.h manually due to GEN calls below.
 GEN('#include "base/command_line.h"');
 
 function CrSettingsCheckboxTest() {}
 
 CrSettingsCheckboxTest.prototype = {
   __proto__: CrSettingsBrowserTest.prototype,
@@ skipping 1384 matching lines @@
 
   /** @override */
   extraLibraries: CrSettingsBrowserTest.prototype.extraLibraries.concat([
     'focusable_iron_list_item_behavior_test.js',
   ]),
 };
 
 TEST_F('CrSettingsFocusableIronListItemBehavior', 'FocusTest', function() {
   mocha.run();
 });