MD Settings: Eliminate Relaunch button flicker at chrome://md-settings/help.

chrome/browser/resources/settings/about_page/about_page.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.
 
 /**
  * @fileoverview 'settings-about-page' contains version and OS related
  * information.
  */
 Polymer({
   is: 'settings-about-page',
 
   behaviors: [WebUIListenerBehavior, MainPageBehavior, I18nBehavior],
 
   properties: {
     /** @private {?UpdateStatusChangedEvent} */
-    currentUpdateStatusEvent_: Object,
+    currentUpdateStatusEvent_: {
+      type: Object,
+      value: {message: '', progress: 0, status: UpdateStatus.DISABLED},
+    },
 
 <if expr="chromeos">
     /** @private */
     hasCheckedForUpdates_: Boolean,
 
     /** @private {!BrowserChannel} */
     currentChannel_: String,
 
     /** @private {!BrowserChannel} */
     targetChannel_: String,
@@ skipping 266 matching lines @@
     });
   },
 
 <if expr="_google_chrome">
   /** @private */
   onReportIssueTap_: function() {
     this.aboutBrowserProxy_.openFeedbackDialog();
   },
 </if>
 });