MD Settings: About: focus radio group after selecting item

chrome/browser/resources/settings/about_page/channel_switcher_dialog.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 'settings-channel-switcher-dialog' is a component allowing the
  * user to switch between release channels (dev, beta, stable). A
  * |target-channel-changed| event is fired if the user does select a different
  * release channel to notify parents of this dialog.
  */
@@ skipping 34 matching lines @@
   /** @private {?settings.AboutPageBrowserProxy} */
   browserProxy_: null,
 
   /** @override */
   ready: function() {
     this.browserProxy_ = settings.AboutPageBrowserProxyImpl.getInstance();
     this.browserProxy_.getChannelInfo().then(function(info) {
       this.currentChannel_ = info.currentChannel;
       this.targetChannel_ = info.targetChannel;
       // Pre-populate radio group with target channel.
-      this.$$('paper-radio-group').select(this.targetChannel_);
+      var radioGroup = this.$$('paper-radio-group');
+      radioGroup.select(this.targetChannel_);
+      radioGroup.focus();
     }.bind(this));
   },
 
   /** @override */
   attached: function() {
     this.$.dialog.showModal();
   },
 
   /** @private */
   onCancelTap_: function() {
@@ skipping 98 matching lines @@
   },
 
   /**
    * @return {boolean}
    * @private
    */
   shouldShowWarning_: function() {
     return this.warning_ !== null;
   },
 });