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

chrome/common/extensions/api/file_manager_private.idl

 // 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.
 
 // fileManagerPrivate API.
 // This is a private API used by the file browser of ChromeOS.
 [platforms=("chromeos"),
  implemented_in="chrome/browser/chromeos/extensions/file_manager/file_manager_private_api_functions.h"]
 namespace fileManagerPrivate {
 // Type of the mounted volume.
@@ skipping 316 matching lines @@
 
   // Flag that specifies if volume is mounted in read-only mode.
   boolean isReadOnly;
 
   // Flag that specifies whether the volume contains media.
   boolean hasMedia;
 
   // Flag that specifies whether the volume is configurable.
   boolean configurable;
 
+  // Flag that specifies whether the volume is watchable.
+  boolean watchable;
+
   // Additional data about mount, for example, that the filesystem is not
   // supported.
   MountCondition? mountCondition;
 
   // Context in which the volume has been mounted.
   MountContext? mountContext;
 };
 
 // Payload data for mount event.
 dictionary MountCompletedEvent {
@@ skipping 174 matching lines @@
 };
 
 // Describes an installed providing extension.
 dictionary ProvidingExtension {
   // ID of the providing extension.
   DOMString extensionId;
 
   // Name of the providing extension.
   DOMString name;
 
   // Whether supports configuration dialog.

[mtomasz, 2015/07/01 08:57:45]

(I'm going to remove configurable and watchable from ProvidingExtension in a
separate CL, as they are already exposed via VolumeMetadata).

   boolean configurable;
 
+  // Whether supports configuration dialog.
+  boolean watchable;
+
   // Whether supports mounting multiple instances.
   boolean multipleMounts;
 
   // Source of file systems' data.
   manifestTypes.FileSystemProviderSource source;
 };
 
 // Callback that does not take arguments.
 callback SimpleCallback = void();
 
@@ skipping 398 matching lines @@
 
   static void onPreferencesChanged();
 
   static void onDriveConnectionStatusChanged();
 
   static void onDeviceChanged(DeviceEvent event);
 
   static void onDriveSyncError(DriveSyncErrorEvent event);
 };
 };