Remove support for the keygen tag

chrome/browser/resources/settings/site_settings_page/site_settings_page.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-settings-page' is the settings page containing privacy and
  * security site settings.
  */
 Polymer({
@@ skipping 28 matching lines @@
         '#automaticDownloads');
     this.setDefaultValue_(this.ContentSettingsTypes.BACKGROUND_SYNC,
         '#backgroundSync');
     this.setDefaultValue_(this.ContentSettingsTypes.CAMERA, '#camera');
     this.setDefaultValue_(this.ContentSettingsTypes.COOKIES, '#cookies');
     this.setDefaultValue_(this.ContentSettingsTypes.GEOLOCATION,
         '#geolocation');
     this.setDefaultValue_(this.ContentSettingsTypes.IMAGES, '#images');
     this.setDefaultValue_(this.ContentSettingsTypes.JAVASCRIPT,
         '#javascript');
-    this.setDefaultValue_(this.ContentSettingsTypes.KEYGEN, '#keygen');
     this.setDefaultValue_(this.ContentSettingsTypes.MIC, '#mic');
     this.setDefaultValue_(this.ContentSettingsTypes.NOTIFICATIONS,
         '#notifications');
     this.setDefaultValue_(this.ContentSettingsTypes.PLUGINS, '#plugins');
     this.setDefaultValue_(this.ContentSettingsTypes.POPUPS, '#popups');
     this.setDefaultValue_(this.ContentSettingsTypes.PROTOCOL_HANDLERS,
         '#handlers');
     this.setDefaultValue_(this.ContentSettingsTypes.UNSANDBOXED_PLUGINS,
         '#unsandboxedPlugins');
   },
 
   setDefaultValue_: function(category, id) {
     this.browserProxy.getDefaultValueForContentType(
         category).then(function(setting) {
           var description = this.computeCategoryDesc(category, setting, false);
           this.$$(id).innerText = description;
         }.bind(this));
   },
 
   /**
    * Navigate to the route specified in the event dataset.
    * @param {!Event} event The tap event.
    * @private
    */
   onTapNavigate_: function(event) {
     var dataSet = /** @type {{route: string}} */(event.currentTarget.dataset);
     settings.navigateTo(settings.Route[dataSet.route]);
   },
 });