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

third_party/closure_compiler/externs/file_manager_private.js

 // Copyright 2014 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.
 
 /** @fileoverview Externs generated from namespace: fileManagerPrivate */
 
 /**
  * @typedef {{
  *   taskId: string,
  *   title: string,
@@ skipping 53 matching lines @@
  *   volumeLabel: (string|undefined),
  *   profile: ProfileInfo,
  *   sourcePath: (string|undefined),
  *   volumeType: string,
  *   deviceType: (string|undefined),
  *   devicePath: (string|undefined),
  *   isParentDevice: (boolean|undefined),
  *   isReadOnly: boolean,
  *   hasMedia: boolean,
  *   configurable: boolean,
+ *   watchable: boolean,
  *   mountCondition: (string|undefined),
  *   mountContext: (string|undefined)
  * }}
  */
 var VolumeMetadata;
 
 /**
  * @typedef {{
  *   eventType: string,
  *   status: string,
@@ skipping 118 matching lines @@
  *   devicePath: string
  * }}
  */
 var DeviceEvent;
 
 /**
  * @typedef {{
  *   extensionId: string,
  *   name: string,
  *   configurable: boolean,
+ *   watchable: boolean,
  *   multipleMounts: boolean,
  *   source: string
  * }}
  */
 var ProvidingExtension;
 
 /**
  * @typedef {{
  *   id: string,
  *   title: (string|undefined)
@@ skipping 438 matching lines @@
 chrome.fileManagerPrivate.onPreferencesChanged;
 
 /** @type {!ChromeEvent} */
 chrome.fileManagerPrivate.onDriveConnectionStatusChanged;
 
 /** @type {!ChromeEvent} */
 chrome.fileManagerPrivate.onDeviceChanged;
 
 /** @type {!ChromeEvent} */
 chrome.fileManagerPrivate.onDriveSyncError;