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

chrome/test/data/webui/settings/basic_page_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 Suite of tests for the Settings basic page. */
 
 GEN_INCLUDE(['settings_page_browsertest.js']);
 
 /**
  * @constructor
@@ skipping 68 matching lines @@
     },
   };
 
   // Register mocha tests.
   suite('SettingsPage', function() {
     test('load page', function() {
       // This will fail if there are any asserts or errors in the Settings page.
     });
 
     test('basic pages', function() {
-      var page = self.getPage('basic');
+      var page = self.page;
       var sections = ['appearance', 'onStartup', 'people', 'search'];
       expectTrue(!!self.getSection(page, 'appearance'));
       if (!cr.isChromeOS)
         sections.push('defaultBrowser');
       else
         sections = sections.concat(['internet', 'bluetooth', 'device']);
 
       for (var i = 0; i < sections.length; i++) {
         var section = self.getSection(page, sections[i]);
         expectTrue(!!section);
         self.verifySubpagesHidden(section);
       }
     });
 
     test('scroll to section', function() {
+      var page = self.page;
       // Setting the page and section will cause a scrollToSection_.
       settings.navigateTo(settings.Route.ON_STARTUP);
 
-      var page = self.getPage('basic');
-
       return new Promise(function(resolve, reject) {
         // This test checks for a regression that occurred with scrollToSection_
         // failing to find its host element.
         var intervalId = window.setInterval(function() {
-          var page = self.getPage('basic');
           if (self.getSection(page, settings.getCurrentRoute().section)) {
             window.clearInterval(intervalId);
             resolve();
           }
         }, 55);
       }.bind(self)).then(function() {
         // Should be scrolled to the On Startup section.
         assertNotEquals(0, page.scroller.scrollTop);
 
         return new Promise(function(resolve) {
           listenOnce(window, 'popstate', resolve);
           settings.navigateToPreviousRoute();
         });
       }).then(function() {
         // Should be at the top of the page after going Back from the section.
         assertEquals(0, page.scroller.scrollTop);
 
         return new Promise(function(resolve) {
           listenOnce(window, 'popstate', resolve);
           window.history.forward();
         });
       }).then(function() {
         // Should scroll when navigating forwards from the BASIC page.
         assertNotEquals(0, page.scroller.scrollTop);
       });
     });
 
     test('scroll to section after exiting search', function() {
+      var page = self.page;
       var searchManager = new TestSearchManager();
       settings.setSearchManagerForTesting(searchManager);
 
       settings.navigateTo(settings.Route.BASIC,
                           new URLSearchParams(`search=foobar`),
                           /* removeSearch */ false);
       return searchManager.whenCalled('search').then(function() {
         return new Promise(function(resolve) {
           settings.navigateTo(settings.Route.ON_STARTUP,
                               /* dynamicParams */ null,
                               /* removeSearch */ true);
 
-          var page = self.getPage('basic');
           assertTrue(!!page);
 
           // Should (after some time) be scrolled to the On Startup section.
           var intervalId = window.setInterval(function() {
             if (page.scroller.scrollTop != 0) {
               window.clearInterval(intervalId);
               resolve();
             }
           }, 55);
         });
       });
     });
 
     test('scroll to top before navigating to about', function() {
-      var page = self.getPage('basic');
+      var page = self.page;
       // Set the viewport small to force the scrollbar to appear on ABOUT.
       Polymer.dom().querySelector('settings-ui').style.height = '200px';
 
       settings.navigateTo(settings.Route.ON_STARTUP);
       assertNotEquals(0, page.scroller.scrollTop);
 
       settings.navigateTo(settings.Route.ABOUT);
       assertEquals(0, page.scroller.scrollTop);
     });
   });
 
   // Run all registered tests.
   mocha.run();
 });