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

chrome/browser/resources/managed_user_passphrase_dialog.js

+// Copyright (c) 2012 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.
+
+function load() {
+  $('unlock-passphrase-button').onclick = function(event) {
+    chrome.send('checkPassphrase', [$('passphrase-entry').value]);
+  };
+  $('cancel-passphrase-button').onclick = function(event) {
+    chrome.send('DialogClose');
+  };
+  $('passphrase-entry').oninput = function(event) {
+    $('unlock-passphrase-button').disabled = $('passphrase-entry').value == '';
+    $('incorrect-passphrase-warning').hidden = true;
+  };
+}
+
+function passphraseCorrect() {
+  chrome.send('DialogClose', ['true']);
+}
+
+function passphraseIncorrect() {
+  $('incorrect-passphrase-warning').hidden = false;
+  $('passphrase-entry').focus();
+}
+
+window.addEventListener('DOMContentLoaded', load);