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

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

Index: chrome/browser/resources/settings/site_settings/site_list.js
diff --git a/chrome/browser/resources/settings/site_settings/site_list.js b/chrome/browser/resources/settings/site_settings/site_list.js
index b3dcb2d037827103fd0ecbb2fd79891160142166..8b79902115bd0c91220e2c538fec02c6129ffc9a 100644
--- a/chrome/browser/resources/settings/site_settings/site_list.js
+++ b/chrome/browser/resources/settings/site_settings/site_list.js
@@ -47,12 +47,6 @@ Polymer({
     },
 
     /**
-     * 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.