Prevented default backspace handler in File Browser Gallery

chrome/browser/resources/file_manager/js/util.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.
 
 /**
  * Namespace for utility functions.
  */
 var util = {
   /**
    * Returns a function that console.log's its arguments, prefixed by |msg|.
@@ skipping 456 matching lines @@
     for (var i = 2; i < arguments.length; i++) {
       var arg = arguments[i];
       if (typeof(arg) == 'string') {
         element.appendChild(document.createTextNode(arg));
       } else {
         element.appendChild(arg);
       }
     }
 
     return element;
+  },
+
+  /**
+   * Returns a string '[Ctrl-][Alt-][Shift-][Meta-]' depending on the event
+   * modifiers. Convenient for writing out conditions in keyboard handlers.
+   *
+   * @param {Event} event
+   * @return {string}
+   */
+  getKeyModifiers: function(event) {
+    return (event.ctrlKey ? 'Ctrl-' : '') +
+           (event.altKey ? 'Alt-' : '') +
+           (event.shiftKey ? 'Shift-' : '') +
+           (event.metaKey ? 'Meta-' : '');
   }
 };