Use dom-if to hide settings pages and show explicitly.

chrome/browser/resources/settings/site_settings/site_list.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.
 
 /**
  * @fileoverview
  * 'settings-site-list' shows a list of Allowed and Blocked sites for a given
  * category.
  *
  * Example:
@@ skipping 29 matching lines @@
     /**
      * Array of sites to display in the widget.
      */
     sites_: {
       type: Array,
       value: function() { return []; },
       observer: 'onDataChanged_',
     },
 
     /**
-     * The ID of the category this widget is displaying data for.
-     * See site_settings/constants.js for possible values.
-     */
-    category: Number,
-
-    /**
       * The type of category this widget is displaying data for. Normally
       * either ALLOW or BLOCK, representing which sites are allowed or blocked
       * respectively.
       */
     categorySubtype: Number,
 
     /**
      * Represents the state of the main toggle shown for the category. For
      * example, the Location category can be set to Block/Ask so false, in that
      * case, represents Block and true represents Ask.
@@ skipping 210 matching lines @@
    * Returns the icon to use for a given site.
    * @param {string} url The url of the site to fetch the icon for.
    * @private
    */
   computeSiteIcon_: function(url) {
     // TODO(finnur): For now, we're returning a placeholder image for each site
     // but the actual favicon for each site will need to be returned.
     return 'communication:message';
   },
 });