MD Settings: On Startup, extract dialog to its own file.

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.
@@ skipping 315 matching lines @@
 
   browsePreload: 'chrome://md-settings/on_startup_page/startup_urls_page.html',
 
   extraLibraries: CrSettingsBrowserTest.prototype.extraLibraries.concat([
     ROOT_PATH + 'ui/webui/resources/js/promise_resolver.js',
     'test_browser_proxy.js',
     'startup_urls_page_test.js',
   ]),
 };
 
-TEST_F('CrSettingsStartupUrlsPageTest', 'Validity', function() {
+TEST_F('CrSettingsStartupUrlsPageTest', 'StartupUrlsPage', function() {
   mocha.run();
 });