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

chrome/browser/system_monitor/media_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::MediaDeviceNotifications implementation.
 
 #include "chrome/browser/system_monitor/media_device_notifications_chromeos.h"
 
 #include "base/file_path.h"
 #include "base/logging.h"
@@ skipping 28 matching lines @@
 }
 
 }  // namespace
 
 using content::BrowserThread;
 
 MediaDeviceNotifications::MediaDeviceNotifications() {
   DCHECK(disks::DiskMountManager::GetInstance());
   disks::DiskMountManager::GetInstance()->AddObserver(this);
   CheckExistingMountPointsOnUIThread();
+  if (base::SystemMonitor::Get())
+    base::SystemMonitor::Get()->set_storage_free_space_delegate(this);
 }
 
 MediaDeviceNotifications::~MediaDeviceNotifications() {
+  if (base::SystemMonitor::Get() &&
+      base::SystemMonitor::Get()->storage_free_space_delegate())
+    base::SystemMonitor::Get()->set_storage_free_space_delegate(NULL);
+
   disks::DiskMountManager* manager = disks::DiskMountManager::GetInstance();
   if (manager) {
     manager->RemoveObserver(this);
   }
 }
 
 void MediaDeviceNotifications::CheckExistingMountPointsOnUIThread() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   const disks::DiskMountManager::MountPointMap& mount_point_map =
       disks::DiskMountManager::GetInstance()->mount_points();
@@ skipping 91 matching lines @@
 
   std::string device_id = chrome::MediaStorageUtil::MakeDeviceId(
       chrome::MediaStorageUtil::REMOVABLE_MASS_STORAGE_WITH_DCIM, 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