MD Settings: Lazy-load sub-pages.

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

Index: chrome/test/data/webui/settings/device_page_tests.js
diff --git a/chrome/test/data/webui/settings/device_page_tests.js b/chrome/test/data/webui/settings/device_page_tests.js
index f22753f66ca87739405cd7f51526d6c92937f69b..75e2340b1b8dde944be560aac054005dcfeb43ee 100644
--- a/chrome/test/data/webui/settings/device_page_tests.js
+++ b/chrome/test/data/webui/settings/device_page_tests.js
@@ -53,11 +53,16 @@ cr.define('settings_device_page', function() {
       value: false,
     }];
 
-    test('keyboard subpage', function() {
-      var devicePage = document.createElement('settings-device-page');
+    var devicePage;
+
+    setup(function() {
+      devicePage = document.createElement('settings-device-page');
       devicePage.currentRoute = {page: 'basic', section: '', subpage: []};
       devicePage.prefs = fakePrefs;
+      Polymer.dom.flush();

[michaelpg, 2016/03/31 02:00:21]

Without this, the light DOM observer isn't called until after a setTimeout. I
think this is because Polymer's observeNodes uses a debouncer to call its
listeners.

+    });
 
+    test('keyboard subpage', function() {
       // Open the keyboard subpage.
       var keyboardRow = devicePage.$$('#main #keyboardRow');
       assertTrue(!!keyboardRow);