[filebrowser] Add left panel with roots.

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

 // Copyright (c) 2011 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 out the chrome.fileBrowserPrivate API for use in the harness.
  */
 chrome.fileBrowserPrivate = {
 
   /**
@@ skipping 199 matching lines @@
     // extension_file_browser_private_api.cc!
     callback({
       // These two are from locale_settings*.grd
       WEB_FONT_FAMILY: 'Chrome Droid Sans,Droid Sans Fallback,sans-serif',
       WEB_FONT_SIZE: '84%',
 
       FILE_IS_DIRECTORY: 'Folder',
       PARENT_DIRECTORY: 'Parent Directory',
 
       ROOT_DIRECTORY_LABEL: 'Files',
-      DOWNLOADS_DIRECTORY_LABEL: 'File Shelf',
+      CHROMEBOOK_DIRECTORY_LABEL: 'Chromebook',
       DOWNLOADS_DIRECTORY_WARNING: "<strong>Caution:</strong> These files are temporary and may be automatically deleted to free up disk space.  <a href='javascript://'>Learn More</a>",
       MEDIA_DIRECTORY_LABEL: 'External Storage',
       NAME_COLUMN_LABEL: 'Name',
       SIZE_COLUMN_LABEL: 'Size',
       TYPE_COLUMN_LABEL: 'Type',
       DATE_COLUMN_LABEL: 'Date',
       PREVIEW_COLUMN_LABEL: 'Preview',
 
       ERROR_CREATING_FOLDER: 'Unable to create folder "$1": $2',
       ERROR_INVALID_CHARACTER: 'Invalid character: $1',
@@ skipping 164 matching lines @@
   }
 };
 
 chrome.metricsPrivate = {
   recordMediumCount: function() {},
   recordSmallCount: function() {},
   recordTime: function() {},
   recordUserAction: function() {},
   recordValue: function() {}
 };