Basic keyboard access for recently_closed menu on NTP (re-work).

chrome/browser/resources/shared/js/cr/ui/menu_item.js

 // Copyright (c) 2012 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.
 
 cr.define('cr.ui', function() {
   /** @const */ var Command = cr.ui.Command;
 
   /**
    * Creates a new menu item element.
    * @param {Object=} opt_propertyBag Optional properties.
@@ skipping 22 matching lines @@
       var commandId;
       if ((commandId = this.getAttribute('command')))
         this.command = commandId;
 
       this.addEventListener('mouseup', this.handleMouseUp_);
 
       // Adding the 'custom-appearance' class prevents widgets.css from changing
       // the appearance of this element.
       this.classList.add('custom-appearance');
 
+      this.setAttribute('role', 'menuitem');
+
       var iconUrl;
       if ((iconUrl = this.getAttribute('icon')))
         this.iconUrl = iconUrl;
     },
 
     /**
      * The command associated with this menu item. If this is set to a string
      * of the form "#element-id" then the element is looked up in the document
      * of the command.
      * @type {cr.ui.Command}
@@ skipping 123 matching lines @@
      * Handles mouseup events. This dispatches an activate event; if there is an
      * associated command, that command is executed.
      * @param {Event} e The mouseup event object.
      * @private
      */
     handleMouseUp_: function(e) {
       if (!this.disabled && !this.isSeparator() && this.selected) {
         // Store |contextElement| since it'll be removed by {Menu} on handling
         // 'activate' event.
         var contextElement = this.parentNode.contextElement;
+        var activationEvent = cr.doc.createEvent('Event');
+        activationEvent.initEvent('activate', true, true);
+        activationEvent.originalEvent = e;
         // Dispatch command event followed by executing the command object.
-        if (cr.dispatchSimpleEvent(this, 'activate', true, true)) {
+        if (this.dispatchEvent(activationEvent)) {
           var command = this.command;
           if (command) {
             command.execute(contextElement);
             cr.ui.swallowDoubleClick(e);
           }
         }
       }
     },
 
     /**
@@ skipping 50 matching lines @@
    * Whether the menu item is checked or not.
    * @type {boolean}
    */
   cr.defineProperty(MenuItem, 'checked', cr.PropertyKind.BOOL_ATTR);
 
   // Export
   return {
     MenuItem: MenuItem
   };
 });