MD Settings: Migrate startup URL action menu to settings-action-menu.

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

 // Copyright 2016 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.
 
 cr.define('settings_startup_urls_page', function() {
   /**
    * @constructor
    * @implements {settings.StartupUrlsPageBrowserProxy}
    * @extends {settings.TestBrowserProxy}
    */
@@ skipping 238 matching lines @@
 
     setup(function() {
       browserProxy = new TestStartupUrlsPageBrowserProxy();
       settings.StartupUrlsPageBrowserProxyImpl.instance_ = browserProxy;
       PolymerTest.clearBody();
       element = document.createElement('settings-startup-url-entry');
       element.model = createSampleUrlEntry();
       document.body.appendChild(element);
 
       // Bring up the popup menu for the following tests to use.
-      assertFalse(!!element.$$('iron-dropdown'));
+      assertFalse(!!element.$$('dialog[is=settings-action-menu]'));
       MockInteractions.tap(element.$.dots);
       Polymer.dom.flush();
-      assertTrue(!!element.$$('iron-dropdown'));
+      assertTrue(!!element.$$('dialog[is=settings-action-menu]'));
     });
 
     teardown(function() { element.remove(); });
 
     test('MenuOptions_Remove', function() {
       var removeButton = element.shadowRoot.querySelector('#remove')
       MockInteractions.tap(removeButton);
       return browserProxy.whenCalled('removeStartupPage').then(
           function(modelIndex) {
             assertEquals(element.model.modelIndex, modelIndex);
           });
     });
   });
 });