Add a lock to the managed user settings page and require authentication for unlocking.

chrome/browser/resources/options/managed_user_set_passphrase.js

 // Copyright (c) 2013 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.
 
 cr.define('options', function() {
   /** @const */ var OptionsPage = options.OptionsPage;
 
   //////////////////////////////////////////////////////////////////////////////
   // ManagedUserSetPassphraseOverlay class:
 
@@ skipping 30 matching lines @@
     updateDisplay_: function() {
       var valid =
           $('passphrase-confirm').value == $('managed-user-passphrase').value;
       $('passphrase-mismatch').hidden = valid;
       $('passphrase-confirm').setCustomValidity(
           valid ? '' : $('passphrase-mismatch').textContent);
       $('save-passphrase').disabled =
           !$('passphrase-confirm').validity.valid ||
           !$('managed-user-passphrase').validity.valid;
     },
+
+    /** @override */
+    canShowPage: function() {
+      return ManagedUserSettings.getInstance().authenticationState ==
+          options.ManagedUserAuthentication.AUTHENTICATED;
+    },
   };
 
   // This is a class used for browsertests.
   var ManagedUserSetPassphraseForTesting = {
     getPassphraseInput: function() {
       return $('managed-user-passphrase');
     },
     getPassphraseConfirmInput: function() {
       return $('passphrase-confirm');
     },
     getSavePassphraseButton: function() {
       return $('save-passphrase');
     },
     updateDisplay: function() {
       return ManagedUserSetPassphraseOverlay.getInstance().updateDisplay_();
     }
   };
 
   // Export
   return {
     ManagedUserSetPassphraseOverlay: ManagedUserSetPassphraseOverlay,
     ManagedUserSetPassphraseForTesting: ManagedUserSetPassphraseForTesting
   };
 
 });