[HBD] Update MD Site Settings Plugins section to show 3rd mode checkbox.

chrome/browser/resources/settings/site_settings/protocol_handlers.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
  * 'protocol-handlers' is the polymer element for showing the
  * protocol handlers category under Site Settings.
  */
 
@@ skipping 60 matching lines @@
     this.browserProxy.initializeProtocolHandlerList();
   },
 
   /**
    * Obtains the description for the main toggle.
    * @param {boolean} categoryEnabled Whether the main toggle is enabled.
    * @return {string} The description to use.
    * @private
    */
   computeHandlersDescription_: function(categoryEnabled) {
+    var setting = categoryEnabled ?
+        settings.PermissionValues.ALLOW : settings.PermissionValues.BLOCK;
     return this.computeCategoryDesc(
-        settings.ContentSettingsTypes.PROTOCOL_HANDLERS, categoryEnabled, true);
+        settings.ContentSettingsTypes.PROTOCOL_HANDLERS, setting, true);
   },
 
   /**
    * Returns whether the given index matches the default handler.
    * @param {number} index The index to evaluate.
    * @param {number} defaultHandler The default handler index.
    * @return {boolean} Whether the item is default.
    * @private
    */
   isDefault_: function(index, defaultHandler) {
@@ skipping 46 matching lines @@
   onActionMenuIronActivate_: function(event) {
     var protocol = event.model.item.protocol;
     var url = event.model.item.spec;
     if (event.detail.selected == MenuActions.SET_DEFAULT) {
       this.browserProxy.setProtocolDefault(protocol, url);
     } else if (event.detail.selected == MenuActions.REMOVE) {
       this.browserProxy.removeProtocolHandler(protocol, url);
     }
   },
 });