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

chrome/browser/chromeos/file_system_provider/service.cc

 // 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.
 
 #include "chrome/browser/chromeos/file_system_provider/service.h"
 
 #include "base/files/file_path.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
 #include "base/stl_util.h"
@@ skipping 154 matching lines @@
   GetProvidingExtensionInfo(extension_id, &provider_info);
   // Store the file system descriptor. Use the mount point name as the file
   // system provider file system id.
   // Examples:
   //   file_system_id = hello_world
   //   mount_point_name =  b33f1337-hello_world-5aa5
   //   writable = false
   //   supports_notify_tag = false
   //   mount_path = /provided/b33f1337-hello_world-5aa5
   //   configurable = true
+  //   watchable = true
   //   source = SOURCE_FILE
   ProvidedFileSystemInfo file_system_info(
       extension_id, options, mount_path,
       provider_info.capabilities.configurable(),
+      provider_info.capabilities.watchable(),
       provider_info.capabilities.source());
 
   ProvidedFileSystemInterface* file_system =
       file_system_factory_.Run(profile_, file_system_info);
   DCHECK(file_system);
   file_system_map_[FileSystemKey(extension_id, options.file_system_id)] =
       file_system;
   mount_point_name_to_key_map_[mount_point_name] =
       FileSystemKey(extension_id, options.file_system_id);
   registry_->RememberFileSystem(file_system_info, *file_system->GetWatchers());
@@ skipping 264 matching lines @@
 }
 
 void Service::OnWatcherListChanged(
     const ProvidedFileSystemInfo& file_system_info,
     const Watchers& watchers) {
   registry_->RememberFileSystem(file_system_info, watchers);
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos