Add a refresh button for providers which do not support watchers.

ui/file_manager/file_manager/foreground/js/ui/banners.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.
 
 /**
  * Responsible for showing following banners in the file list.
  *  - WelcomeBanner
  *  - AuthFailBanner
  * @param {DirectoryModel} directoryModel The model.
  * @param {VolumeManagerWrapper} volumeManager The manager.
@@ skipping 194 matching lines @@
     var moreInnerButton = util.createChild(
         more, 'imitate-paper-button primary', 'button');
     moreInnerButton.tabIndex = '-1';
     moreInnerButton.textContent = str('DRIVE_WELCOME_CHECK_ELIGIBILITY');
   } else {
     title.textContent = str('DRIVE_WELCOME_TITLE');
     more = util.createChild(links, 'plain-link', 'a');
     more.textContent = str('DRIVE_LEARN_MORE');
     more.href = str('GOOGLE_DRIVE_OVERVIEW_URL');
   }
-  more.tabIndex = '20';  // See: go/filesapp-tabindex.
+  more.tabIndex = '21';  // See: go/filesapp-tabindex.
   more.id = 'drive-welcome-link';
   more.target = '_blank';
 
   var dismiss;
   if (this.usePromoWelcomeBanner_) {
     dismiss = util.createChild(
         links, 'imitate-paper-button secondary', 'button');
   } else {
     dismiss = util.createChild(links, 'plain-link');
   }
@@ skipping 474 matching lines @@
  * @private
  */
 Banners.prototype.maybeShowAuthFailBanner_ = function() {
   var connection = this.volumeManager_.getDriveConnectionState();
   var showDriveNotReachedMessage =
       this.isOnCurrentProfileDrive() &&
       connection.type == VolumeManagerCommon.DriveConnectionType.OFFLINE &&
       connection.reason == VolumeManagerCommon.DriveConnectionReason.NOT_READY;
   this.authFailedBanner_.hidden = !showDriveNotReachedMessage;
 };