Simplifed logic of showing/hiding cancel buttons on login screens.

chrome/browser/resources/chromeos/login/screen_error_message.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.
 
 /**
  * @fileoverview Offline message screen implementation.
  */
 
 login.createScreen('ErrorMessageScreen', 'error-message', function() {
   var CONTEXT_KEY_ERROR_STATE_CODE = 'error-state-code';
@@ skipping 71 matching lines @@
       'setErrorState',
       'showConnectingIndicator'
     ],
 
     // Error screen initial UI state.
     ui_state_: ERROR_SCREEN_UI_STATE.UNKNOWN,
 
     // Error screen initial error state.
     error_state_: ERROR_STATE.UNKNOWN,
 
+    // Whether the screen can be cancelled.
+    cancelable_: false,
+    get cancelable() {
+      return this.cancelable_;
+    },
+    set cancelable(value) {
+      this.cancelable_ = value;
+      $('error-close-button').hidden = !value;
+    },
+
     /** @override */
     decorate: function() {
       cr.ui.DropDown.decorate($('offline-networks-list'));
       this.updateLocalizedContent();
 
       var self = this;
       this.context.addObserver(CONTEXT_KEY_ERROR_STATE_CODE,
                                function(error_state) {
         self.setErrorState(error_state);
       });
@@ skipping 113 matching lines @@
     },
 
     /**
      * Event handler that is invoked just before the screen in shown.
      * @param {Object} data Screen init payload.
      */
     onBeforeShow: function(data) {
       cr.ui.Oobe.clearErrors();
       cr.ui.DropDown.show('offline-networks-list', false);
       $('login-header-bar').signinUIState = SIGNIN_UI_STATE.ERROR;
-      $('error-close-button').hidden = !$('login-header-bar').allowCancel;
+      this.cancelable = $('pod-row').pods.length;
     },
 
     /**
      * Event handler that is invoked just before the screen is hidden.
      */
     onBeforeHide: function() {
       cr.ui.DropDown.hide('offline-networks-list');
       $('login-header-bar').signinUIState = SIGNIN_UI_STATE.HIDDEN;
     },
 
@@ skipping 180 matching lines @@
      */
     showConnectingIndicator: function(show) {
       this.classList.toggle('show-connecting-indicator', show);
       this.onContentChange_();
     },
 
     /**
      * Cancels error screen and drops to user pods.
      */
     cancel: function() {
-      if ($('login-header-bar').allowCancel)
+      if (this.cancelable)
         Oobe.showUserPods();
     }
   };
 });