Add the code to delete the unused folder-shortcut data

chrome/browser/resources/file_manager/js/file_manager.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.
 
 'use strict';
 
 /**
  * This variable is checked in SelectFileDialogExtensionBrowserTest.
  * @type {number}
  */
@@ skipping 228 matching lines @@
 
     // Get the command line option.
     group.add(function(done) {
       chrome.commandLinePrivate.hasSwitch(
           'file-manager-show-checkboxes', function(flag) {
         this.showCheckboxes_ = flag;
         done();
       }.bind(this));
     }.bind(this));
 
+    // Removes the user data which is no longer used.
+    // TODO(yoshiki): Remove this in M31 http://crbug.com/268784/
+    chrome.storage.local.remove('folder-shortcuts-list');
+
     group.run(callback);
   };
 
   /**
    * Request local file system, resolve roots and init_ after that.
    * Warning, you can't use DOM nor any external scripts here, since it may not
    * be loaded yet. Functions in util.* and metrics.* are available and can
    * be used.
    *
    * @param {function()} callback Completion callback.
@@ skipping 3609 matching lines @@
    */
   FileManager.prototype.setCtrlKeyPressed_ = function(flag) {
     this.ctrlKeyPressed_ = flag;
     // Before the DOM is constructed, the key event can be handled.
     var cacheClearCommand =
         this.document_.querySelector('#drive-clear-local-cache');
     if (cacheClearCommand)
       cacheClearCommand.canExecuteChange();
   };
 })();