Make MD Settings side bar keyboard accessible.

chrome/browser/resources/settings/settings_menu/settings_menu.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-menu' shows a menu with a hardcoded set of pages and subpages.
  */
 Polymer({
   is: 'settings-menu',
@@ skipping 55 matching lines @@
       // For routes from URL entry, we need to set selected.
       this.$.basicMenu.selected = newRoute.path;
     }
   },
 
   /**
    * @param {!Event} event
    * @private
    */
   openPage_: function(event) {
-    var route = settings.getRouteForPath(event.currentTarget.dataset.path);
+    event.preventDefault();
+    var path = event.currentTarget.href.substr(

[Dan Beam, 2017/02/06 17:28:12]

btw, there's a URL class

new URL(event.currentTarget.href).pathname

but in this case you can just call getAttribute('href')

https://jsfiddle.net/00reaL2o/

[hcarmona, 2017/02/10 19:27:34]

Sweet! Using URL.

+        event.currentTarget.baseURI.length - 1);

[dschuyler, 2017/02/02 20:46:53]

My guess is that line 77 is cutting off any query parameters there may be - is
that right? Hmm, how about a comment saying what this is doing?

[hcarmona, 2017/02/10 19:27:34]

Changed to use URL

+    var route = settings.getRouteForPath(path);
     assert(route, 'settings-menu has an an entry with an invalid path');
     settings.navigateTo(
         route, /* dynamicParams */ null, /* removeSearch */ true);
   },
 
   /**
    * @param {boolean} opened Whether the menu is expanded.
    * @return {string} Which icon to use.
    * @private
    * */
   arrowState_: function(opened) {
     return opened ? 'cr:arrow-drop-up' : 'cr:arrow-drop-down';
   },
 });