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

chrome/browser/system_monitor/removable_device_notifications_chromeos.h

 // 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 listens for mount point changes
 // and notifies the SystemMonitor about the addition and deletion of media
 // devices.
 
 #ifndef CHROME_BROWSER_SYSTEM_MONITOR_REMOVABLE_DEVICE_NOTIFICATIONS_CHROMEOS_H_
 #define CHROME_BROWSER_SYSTEM_MONITOR_REMOVABLE_DEVICE_NOTIFICATIONS_CHROMEOS_H_
 
 #if !defined(OS_CHROMEOS)
 #error "Should only be used on ChromeOS."
 #endif
 
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/system_monitor/system_monitor.h"
 #include "chromeos/disks/disk_mount_manager.h"
 
 namespace chromeos {
 
 class RemovableDeviceNotificationsCros
     : public base::RefCountedThreadSafe<RemovableDeviceNotificationsCros>,
       public disks::DiskMountManager::Observer {
+      public base::SystemMonitor::StorageFreeSpaceDelegate {
  public:
   RemovableDeviceNotificationsCros();
 
   virtual void DiskChanged(disks::DiskMountManagerEventType event,
                            const disks::DiskMountManager::Disk* disk) OVERRIDE;
   virtual void DeviceChanged(disks::DiskMountManagerEventType event,
                              const std::string& device_path) OVERRIDE;
   virtual void MountCompleted(
       disks::DiskMountManager::MountEvent event_type,
       MountError error_code,
@@ skipping 17 matching lines @@
   void CheckMountedPathOnFileThread(
       const disks::DiskMountManager::MountPointInfo& mount_info);
 
   // Adds the mount point in |mount_info| to |mount_map_| and send a media
   // device attach notification. |has_dcim| is true if the attached device has
   // a DCIM folder.
   void AddMountedPathOnUIThread(
       const disks::DiskMountManager::MountPointInfo& mount_info,
       bool has_dcim);
 
+  // Overriden from SystemMonitor::StorageFreeSpaceDelegate.
+  virtual void StartWatchingStorage(const FilePath& path) OVERRIDE;
+  virtual void StopWatchingStorage(const FilePath& path) OVERRIDE;
+
   // Mapping of relevant mount points and their corresponding mount devices.
   // Only accessed on the UI thread.
   MountMap mount_map_;
 
   DISALLOW_COPY_AND_ASSIGN(RemovableDeviceNotificationsCros);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_SYSTEM_MONITOR_REMOVABLE_DEVICE_NOTIFICATIONS_CHROMEOS_H_