Add the code to delete the unused folder-shortcut data

chrome/browser/resources/file_manager/js/file_manager.js

Index: chrome/browser/resources/file_manager/js/file_manager.js
diff --git a/chrome/browser/resources/file_manager/js/file_manager.js b/chrome/browser/resources/file_manager/js/file_manager.js
index 42653869d05ab561f9ddda424e4e0f277c5bedc2..b3afd909cd38927bdeaaf79fc19430e8348e0d54 100644
--- a/chrome/browser/resources/file_manager/js/file_manager.js
+++ b/chrome/browser/resources/file_manager/js/file_manager.js
@@ -246,6 +246,10 @@ var BOTTOM_MARGIN_FOR_PREVIEW_PANEL_PX = 52;
       }.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);
   };