MD Settings: Fix case where "Check for updates" is accidentally shown.

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',
@@ skipping 355 matching lines @@
   onCheckUpdatesTap_: function() {
     this.onUpdateStatusChanged_({status: UpdateStatus.CHECKING});
     this.aboutBrowserProxy_.requestUpdate();
   },
 
   /**
    * @return {boolean}
    * @private
    */
   computeShowCheckUpdates_: function() {
-    return !this.hasCheckedForUpdates_ ||
-        this.checkStatus_(UpdateStatus.FAILED);
+    // Enable the update button if we are in a stale 'updated' status or
+    // update has failed. Disable it otherwise.
+    var staleUpdatedStatus = !this.hasCheckedForUpdates_ &&
+        this.checkStatus_(UpdateStatus.UPDATED);
+
+    return staleUpdatedStatus || this.checkStatus_(UpdateStatus.FAILED);
   },
 
   /**
    * @return {boolean}
    * @private
    */
   shouldShowRegulatoryInfo_: function() {
     return this.regulatoryInfo_ !== null;
   },
 // </if>
 
   /** @private */
   onProductLogoTap_: function() {
     this.$['product-logo'].animate({
       transform: ['none', 'rotate(-10turn)'],
     }, {
       duration: 500,
       easing: 'cubic-bezier(1, 0, 0, 1)',
     });
   },
 
 // <if expr="_google_chrome">
   /** @private */
   onReportIssueTap_: function() {
     this.aboutBrowserProxy_.openFeedbackDialog();
   },
 // </if>
 });