Convert Event#keyIdentifier (deprecated) to Event#key

ui/webui/resources/js/cr/ui/menu_button.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.
 
 // <include src="../../assert.js">
 
 cr.exportPath('cr.ui');
 
 /**
  * Enum for type of hide. Delayed is used when called by clicking on a
@@ skipping 248 matching lines @@
      */
     positionMenu_: function() {
       positionPopupAroundElement(this, this.menu, this.anchorType,
                                  this.invertLeftRight);
     },
 
     /**
      * Handles the keydown event for the menu button.
      */
     handleKeyDown: function(e) {
-      switch (e.keyIdentifier) {
-        case 'Down':
-        case 'Up':
+      switch (e.key) {
+        case 'ArrowDown':
+        case 'ArrowUp':
           if (!this.respondToArrowKeys)
             break;
         case 'Enter':
-        case 'U+0020': // Space
+        case ' ':
           if (!this.isMenuShown())
             this.showMenu(true);
           e.preventDefault();
           break;
-        case 'Esc':
-        case 'U+001B': // Maybe this is remote desktop playing a prank?
-        case 'U+0009': // Tab
+        case 'Escape':
+        case 'Tab':
           this.hideMenu();
           break;
       }
     }
   };
 
   // Export
   return {
     MenuButton: MenuButton,
   };
 });