Settings: Cookies: Avoid duplicate 'incognito' exceptions in CrOS Guest mode

chrome/browser/resources/settings/site_settings/add_site_dialog.js

 // Copyright 2016 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
  * 'add-site-dialog' provides a dialog to add exceptions for a given Content
  * Settings category.
  */
 Polymer({
@@ skipping 28 matching lines @@
   attached: function() {
     assert(this.category);
     assert(this.contentSetting);
   },
 
   /** Open the dialog. */
   open: function() {
     this.addWebUIListener('onIncognitoStatusChanged', function(hasIncognito) {
       this.$.incognito.checked = false;
       this.showIncognitoSessionOnly_ = hasIncognito &&
+          !loadTimeData.getBoolean('isGuest') &&
           this.contentSetting != settings.PermissionValues.SESSION_ONLY;
     }.bind(this));
     this.browserProxy.updateIncognitoStatus();
     this.$.dialog.showModal();
   },
 
   /**
    * Validates that the pattern entered is valid.
    * @private
    */
@@ skipping 24 matching lines @@
    */
   onSubmit_: function() {
     if (this.$.add.disabled)
       return;  // Can happen when Enter is pressed.
     this.browserProxy.setCategoryPermissionForOrigin(
         this.site_, this.site_, this.category, this.contentSetting,
         this.$.incognito.checked);
     this.$.dialog.close();
   },
 });