Site Settings Desktop: Implement protocol handler section.

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.
  */
 Polymer({
@@ skipping 225 matching lines @@
   },
 
   /**
    * Retrieves a list of all known sites (any category/setting).
    * @return {!Promise}
    * @private
    */
   getAllSitesList_: function() {
     var promiseList = [];
     for (var type in settings.ContentSettingsTypes) {
+      if (settings.ContentSettingsTypes[type] ==
+          settings.ContentSettingsTypes.PROTOCOL_HANDLERS) {
+        // Protocol handlers don't have data stored the way all the other
+        // categories do.
+        continue;
+      }
+
       promiseList.push(
           this.browserProxy_.getExceptionList(
               settings.ContentSettingsTypes[type]));
     }
 
     return Promise.all(promiseList);
   },
 
   /**
    * Appends to |list| the sites for a given category and subtype.
@@ skipping 201 matching lines @@
     // is redundant to also list all the sites that are blocked.
     if (this.isAllowList_())
       return true;
 
     if (this.isSessionOnlyList_())
       return siteList.length > 0;
 
     return toggleState;
   },
 });