Extend the capability of SystemMonitor to support watching storage free space change

chrome/browser/system_monitor/removable_device_notifications_chromeos.cc

 // 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.
 
 // chromeos::RemovableDeviceNotificationsCros implementation.
 
 #include "chrome/browser/system_monitor/removable_device_notifications_chromeos.h"
 
 #include "base/file_path.h"
 #include "base/logging.h"
@@ skipping 149 matching lines @@
 
   std::string device_id = chrome::MediaStorageUtil::MakeDeviceId(type,
                                                                  unique_id);
   mount_map_.insert(std::make_pair(mount_info.mount_path, device_id));
   base::SystemMonitor::Get()->ProcessRemovableStorageAttached(
       device_id,
       device_label,
       mount_info.mount_path);
 }
 
+void MediaDeviceNotifications::StartWatchingStorage(const FilePath& path) {
+  NOTIMPLEMENTED();
+}
+
+void MediaDeviceNotifications::StopWatchingStorage(const FilePath& path) {
+  NOTIMPLEMENTED();
+}
+
 }  // namespace chrome