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

chrome/browser/system_monitor/removable_device_notifications_linux.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.
 
 // RemovableDeviceNotificationsLinux implementation.
 
 #include "chrome/browser/system_monitor/removable_device_notifications_linux.h"
 
 #include <libudev.h>
 #include <mntent.h>
@@ skipping 491 matching lines @@
 
   mount_info_map_[mount_point] = mount_point_info;
   mount_priority_map_[mount_device][mount_point] = removable;
 
   if (removable) {
     SystemMonitor::Get()->ProcessRemovableStorageAttached(device_id, name,
                                                           mount_point.value());
   }
 }
 
+bool RemovableDeviceNotificationsLinux::StartWatchingStorage(
+    const FilePath::StringType& path) {
+  return false;
+}
+
+bool RemovableDeviceNotificationsLinux::StopWatchingStorage(
+    const FilePath::StringType& path) {
+  return false;
+}
+
 }  // namespace chrome