[MD settings] adding a test for Appearance settings

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

Index: chrome/test/data/webui/settings/settings_page_browsertest.js
diff --git a/chrome/test/data/webui/settings/settings_page_browsertest.js b/chrome/test/data/webui/settings/settings_page_browsertest.js
index 2b8e53d2afbd2ca0e7258940699d20d58446fe5a..28570ae02fc232a16ed730c42e5265c6e98389b3 100644
--- a/chrome/test/data/webui/settings/settings_page_browsertest.js
+++ b/chrome/test/data/webui/settings/settings_page_browsertest.js
@@ -29,6 +29,13 @@ SettingsPageBrowserTest.prototype = {
   /** @override */
   runAccessibilityChecks: false,
 
+  /** @override */
+  setUp: function() {
+    suiteSetup(function() {
+      return CrSettingsPrefs.initialized;
+    });
+  },
+
   /**
    * @param {string} type The settings page type, e.g. 'advanced' or 'basic'.
    * @return {Node} The DOM node for the page.