MD Settings: Move browserProxies outside of Polymer "properties".

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({
   is: 'settings-startup-urls-page',
 
   behaviors: [CrScrollableBehavior, WebUIListenerBehavior],
 
   properties: {
     prefs: Object,
 
-    /** @type {settings.StartupUrlsPageBrowserProxy} */
-    browserProxy_: Object,
-
     /**
      * Pages to load upon browser startup.
      * @private {!Array<!StartupPageInfo>}
      */
     startupPages_: Array,
 
     /** @private */
     showStartupUrlDialog_: Boolean,
 
     /** @private {?StartupPageInfo} */
     startupUrlDialogModel_: Object,
 
     /** @private {Object}*/
     lastFocused_: Object,
   },
 
+  /** @private {?settings.StartupUrlsPageBrowserProxy} */
+  browserProxy_: null,
+
   /**
    * The element to return focus to, when the startup-url-dialog is closed.
    * @private {?HTMLElement}
    */
   startupUrlDialogAnchor_: null,
 
   /** @override */
   attached: function() {
     this.browserProxy_ = settings.StartupUrlsPageBrowserProxyImpl.getInstance();
     this.addWebUIListener('update-startup-pages', function(startupPages) {
@@ skipping 33 matching lines @@
       this.startupUrlDialogAnchor_.focus();
       this.startupUrlDialogAnchor_ = null;
     }
   },
 
   /** @private */
   onUseCurrentPagesTap_: function() {
     this.browserProxy_.useCurrentPages();
   },
 });