filemanager: Files App change necessary to use "drive/root". It still works with "drive".

chrome/browser/resources/file_manager/js/volume_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.
 
 /**
  * VolumeManager is responsible for tracking list of mounted volumes.
  *
  * @constructor
  * @extends {cr.EventTarget}
  */
@@ skipping 502 matching lines @@
       return;
   }
   throw new Error('Invalid mount error: ', error);
 };
 
 /**
  * @param {string} mountPath Mount path.
  * @private
  */
 VolumeManager.prototype.validateMountPath_ = function(mountPath) {
-  if (!/^\/(((archive|removable)\/[^\/]+)|drive|drive_offline|Downloads)$/.
-      test(mountPath))
+  console.log(mountPath);
+  if (!/^\/(drive|drive_offline|Downloads)$/.test(mountPath) &&
+      !/^\/((archive|removable|drive)\/[^\/]+)$/.test(mountPath))
     throw new Error('Invalid mount path: ', mountPath);
 };