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

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

Index: chrome/test/data/webui/settings/settings_subpage_browsertest.js
diff --git a/chrome/test/data/webui/settings/settings_subpage_browsertest.js b/chrome/test/data/webui/settings/settings_subpage_browsertest.js
index 5e32e649e720d5a943e7c90fa4946d17ab0429a8..b8e539a464cfb709b0bc576b578488739b1f5bd3 100644
--- a/chrome/test/data/webui/settings/settings_subpage_browsertest.js
+++ b/chrome/test/data/webui/settings/settings_subpage_browsertest.js
@@ -12,14 +12,8 @@ GEN_INCLUDE(['settings_page_browsertest.js']);
 /**
  * @constructor
  * @extends {SettingsPageBrowserTest}
- *
- * @param {string} pageId Just 'basic'. TODO(michaelpg): Add 'about' if we want
- *     to, but that requires wrapping its sole <settings-section> in a dom-if.
  */
-function SettingsSubPageBrowserTest(pageId) {
-  /** @type {string} */
-  this.pageId = pageId;
-
+function SettingsSubPageBrowserTest() {
   /** @type {!Array<string>} */
   this.subPages = [];
 }
@@ -36,18 +30,12 @@ SettingsSubPageBrowserTest.prototype = {
     settingsHidePagesByDefaultForTest = true;
   },
 
-  /** @override */
-  setUp: function() {
-    SettingsPageBrowserTest.prototype.setUp.call(this);
-    this.verifySubPagesHidden_();
-  },
-
   /*
    * Checks all subpages are hidden first.
    * @private
    */
   verifySubPagesHidden_: function() {
-    var page = this.getPage(this.pageId);
+    var page = this.page;
     assertEquals(0, Object.keys(page.pageVisibility).length);
 
     // Ensure all pages are still hidden after the dom-ifs compute their |if|.
@@ -79,9 +67,11 @@ SettingsSubPageBrowserTest.prototype = {
   },
 
   testSubPages: function() {
-    var page = this.getPage(this.pageId);
     this.subPages.forEach(function(subPage) {
-      test(subPage, this.testSubPage.bind(this, page, subPage));
+      test(subPage, function() {
+        this.verifySubPagesHidden_();
+        this.testSubPage(this.page, subPage);
+      }.bind(this));
     }.bind(this));
   },
 };