Files.app: Remove navigationVolumeMap from the background page.

chrome/test/data/file_manager/unit_tests/mocks/mock_volume_manager.js

 // Copyright 2013 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.
 
 /**
  * Mock class for VolumeManager.
  * @constructor
  */
 function MockVolumeManager() {
   this.volumeInfoList = new cr.ui.ArrayDataModel([]);
@@ skipping 26 matching lines @@
  */
 MockVolumeManager.createMockVolumeInfo = function(type, volumeId) {
   var fileSystem = new MockFileSystem(volumeId);
 
   var volumeInfo = new VolumeInfo(
       type,
       volumeId,
       fileSystem,
       '',     // error
       '',     // deviceType
+      '',     // devicePath
       false,  // isReadonly
       {isCurrentProfile: true, displayName: ''},  // profile
       '');    // label
 
   return volumeInfo;
 };