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

chrome/browser/system_monitor/removable_device_notifications_linux.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.
 
 // RemovableDeviceNotificationsLinux listens for mount point changes, notifies
 // the SystemMonitor about the addition and deletion of media devices, and
 // answers queries about mounted devices.
 
 #ifndef CHROME_BROWSER_SYSTEM_MONITOR_REMOVABLE_DEVICE_NOTIFICATIONS_LINUX_H_
 #define CHROME_BROWSER_SYSTEM_MONITOR_REMOVABLE_DEVICE_NOTIFICATIONS_LINUX_H_
@@ skipping 19 matching lines @@
 // Gets device information given a |device_path|. On success, fills in
 // |unique_id|, |name|, and |removable|.
 typedef void (*GetDeviceInfoFunc)(const FilePath& device_path,
                                   std::string* unique_id, string16* name,
                                   bool* removable);
 
 namespace chrome {
 
 class RemovableDeviceNotificationsLinux
     : public base::RefCountedThreadSafe<RemovableDeviceNotificationsLinux,
-          content::BrowserThread::DeleteOnFileThread> {
+          content::BrowserThread::DeleteOnFileThread>,
+      public base::SystemMonitor::StorageFreeSpaceDelegate {
  public:
   // Should only be called by browser start up code.  Use GetInstance() instead.
   explicit RemovableDeviceNotificationsLinux(const FilePath& path);
 
   static RemovableDeviceNotificationsLinux* GetInstance();
 
   // Must be called for RemovableDeviceNotificationsLinux to work.
   void Init();
 
   // Use |device_id| to find and return where the device is mounted.
@@ skipping 50 matching lines @@
   // Do initialization on the File Thread.
   void InitOnFileThread();
 
   // Parses mtab file and find all changes.
   void UpdateMtab();
 
   // Adds |mount_device| as mounted on |mount_point|.  If the device is a new
   // device SystemMonitor is notified.
   void AddNewMount(const FilePath& mount_device, const FilePath& mount_point);
 
+  // Overriden from SystemMonitor::StorageFreeSpaceDelegate.
+  virtual void StartWatchingStorage(const FilePath& path) OVERRIDE;
+  virtual void StopWatchingStorage(const FilePath& path) OVERRIDE;
+
   // Whether Init() has been called or not.
   bool initialized_;
 
   // Mtab file that lists the mount points.
   const FilePath mtab_path_;
 
   // Watcher for |mtab_path_|.
   base::files::FilePathWatcher file_watcher_;
 
   // Set of known file systems that we care about.
@@ skipping 13 matching lines @@
   // to notify about it's departure and notify about another one of it's mount
   // points.
   MountPriorityMap mount_priority_map_;
 
   DISALLOW_COPY_AND_ASSIGN(RemovableDeviceNotificationsLinux);
 };
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_SYSTEM_MONITOR_REMOVABLE_DEVICE_NOTIFICATIONS_LINUX_H_