Settings to control Add Person and Browse as Guest.

chrome/browser/resources/user_manager/user_manager.js

 // Copyright 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.
 <include src="../../../../ui/login/screen.js">
 <include src="../../../../ui/login/bubble.js">
 <include src="../../../../ui/login/login_ui_tools.js">
 <include src="../../../../ui/login/display_manager.js">
 <include src="control_bar.js">
 <include src="../../../../ui/login/account_picker/screen_account_picker.js">
 <include src="../../../../ui/login/account_picker/user_pod_row.js">
@@ skipping 14 matching lines @@
   }
 
   cr.addSingletonGetter(Oobe);
 
   Oobe.prototype = {
     __proto__: DisplayManager.prototype,
   };
 
   /**
    * Shows the given screen.
    * @param {Object} screen Screen params dict, e.g. {id: screenId, data: data}

[Marc Treib, 2014/09/01 08:49:53]

nit: The comment is inaccurate/out-of-date (not your fault of course, but would
still be nice to fix)

[Mike Lerman, 2014/09/02 16:58:29]

Done.

    */
-  Oobe.showUserManagerScreen = function(showGuest) {
+  Oobe.showUserManagerScreen = function(showGuest, showAddPerson) {
     Oobe.getInstance().showScreen({id: 'account-picker',
                                    data: {disableAddUser: false}});
     // The ChromeOS account-picker will hide the AddUser button if a user is
     // logged in and the screen is "locked", so we must re-enabled it
     $('add-user-header-bar-item').hidden = false;
 
-    // Hide the Guest Mode option if the user is not permitted to select it.
+    // Hide control options if the user does not have the right permissions.
     $('guest-user-button').hidden = !showGuest;
+    $('add-user-button').hidden = !showAddPerson;
     $('login-header-bar').hidden = false;
 
     // Disable the context menu, as the Print/Inspect element items don't
     // make sense when displayed as a widget.
     document.addEventListener('contextmenu', function(e) {e.preventDefault();});
 
     var hash = window.location.hash;
     if (hash && hash == '#tutorial')
       UserManagerTutorial.startTutorial();
   };
@@ skipping 96 matching lines @@
 // Allow selection events on components with editable text (password field)
 // bug (http://code.google.com/p/chromium/issues/detail?id=125863)
 disableTextSelectAndDrag(function(e) {
   var src = e.target;
   return src instanceof HTMLTextAreaElement ||
          src instanceof HTMLInputElement &&
          /text|password|search/.test(src.type);
 });
 
 document.addEventListener('DOMContentLoaded', UserManager.initialize);