Remove the use of KeyEvent.keyIdentifier.

ui/file_manager/file_manager/foreground/js/ui/combobutton.js

Index: ui/file_manager/file_manager/foreground/js/ui/combobutton.js
diff --git a/ui/file_manager/file_manager/foreground/js/ui/combobutton.js b/ui/file_manager/file_manager/foreground/js/ui/combobutton.js
index 4e66457ce066c47153f4e076ffe110762d3216b5..3fb3503a4c5e360e6555f258880d8f32b21cf1e3 100644
--- a/ui/file_manager/file_manager/foreground/js/ui/combobutton.js
+++ b/ui/file_manager/file_manager/foreground/js/ui/combobutton.js
@@ -123,15 +123,14 @@ cr.define('cr.ui', function() {
      * 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.isMenuShown())
             this.showMenu(false);
           e.preventDefault();
           break;
-        case 'Esc':
-        case 'U+001B': // Maybe this is remote desktop playing a prank?
+        case 'Escape': // Maybe this is remote desktop playing a prank?
           this.hideMenu();
           break;
       }