MD Settings: adjust iron-list focus row behaviors.

chrome/browser/resources/settings/on_startup_page/startup_urls_page.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 'settings-startup-urls-page' is the settings page
  * containing the urls that will be opened when chrome is started.
  */
 
 Polymer({
@@ skipping 11 matching lines @@
      * Pages to load upon browser startup.
      * @private {!Array<!StartupPageInfo>}
      */
     startupPages_: Array,
 
     /** @private */
     showStartupUrlDialog_: Boolean,
 
     /** @private {?StartupPageInfo} */
     startupUrlDialogModel_: Object,
+
+    /** @private {Object}*/
+    lastFocused_: Object,
   },
 
   /** @override */
   attached: function() {
     this.browserProxy_ = settings.StartupUrlsPageBrowserProxyImpl.getInstance();
     this.addWebUIListener('update-startup-pages', function(startupPages) {
       // If an "edit" URL dialog was open, close it, because the underlying page
       // might have just been removed (and model indices have changed anyway).
       if (this.startupUrlDialogModel_)
         this.destroyUrlDialog_();
@@ skipping 22 matching lines @@
   destroyUrlDialog_: function() {
     this.showStartupUrlDialog_ = false;
     this.startupUrlDialogModel_ = null;
   },
 
   /** @private */
   onUseCurrentPagesTap_: function() {
     this.browserProxy_.useCurrentPages();
   },
 });