Site Settings Desktop: Implement Zoom Levels category.

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

 // Copyright 2015 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('settings', function() {
   /**
    * All possible contentSettingsTypes that we currently support configuring in
    * the UI. Both top-level categories and content settings that represent
    * individual permissions under Site Details should appear here. This is a
    * subset of the constants found in site_settings_helper.cc and the values
@@ skipping 10 matching lines @@
     NOTIFICATIONS: 'notifications',
     FULLSCREEN: 'fullscreen',
     MIC: 'media-stream-mic',
     CAMERA: 'media-stream-camera',
     PROTOCOL_HANDLERS: 'register-protocol-handler',
     UNSANDBOXED_PLUGINS: 'ppapi-broker',
     AUTOMATIC_DOWNLOADS: 'multiple-automatic-downloads',
     KEYGEN: 'keygen',
     BACKGROUND_SYNC: 'background-sync',
     USB_DEVICES: 'usb-chooser-data',
+    ZOOM_LEVELS: 'zoom-levels',
   };
 
   /**
    * Contains the possible string values for a given contentSettingsType.
    * @enum {string}
    */
   var PermissionValues = {
     DEFAULT: 'default',
     ALLOW: 'allow',
     BLOCK: 'block',
@@ skipping 14 matching lines @@
    */
   var INVALID_CATEGORY_SUBTYPE = '';
 
   return {
     ContentSettingsTypes: ContentSettingsTypes,
     PermissionValues: PermissionValues,
     ALL_SITES: ALL_SITES,
     INVALID_CATEGORY_SUBTYPE: INVALID_CATEGORY_SUBTYPE,
   };
 });