MD Settings: hide signin-related UI when signin is disabled (e.g. by policy)

chrome/browser/resources/settings/people_page/people_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-people-page' is the settings page containing sign-in settings.
  */
 Polymer({
   is: 'settings-people-page',
@@ skipping 340 matching lines @@
   },
 
   /**
    * @param {string} iconUrl
    * @return {string} A CSS imageset for multiple scale factors.
    * @private
    */
   getIconImageset_: function(iconUrl) {
     return cr.icon.getImage(iconUrl);
   },
+
+  /**
+   * @return {boolean} Whether to show the "Sign in to Chrome" button.
+   * @private
+   */
+  showSignin_: function(syncStatus) {
+    return syncStatus.signinAllowed && !syncStatus.signedIn;
+  },
 });