Extend system monitor capacity for watching the free space changes

base/system_monitor/system_monitor.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.
 
 #ifndef BASE_SYSTEM_MONITOR_SYSTEM_MONITOR_H_
 #define BASE_SYSTEM_MONITOR_SYSTEM_MONITOR_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/file_path.h"
+#include "base/files/file_path_watcher.h"
 #include "base/string16.h"
 #include "build/build_config.h"
 
 // Windows HiRes timers drain the battery faster so we need to know the battery
 // status.  This isn't true for other platforms.
 #if defined(OS_WIN)
 #define ENABLE_BATTERY_MONITORING 1
 #else
 #undef ENABLE_BATTERY_MONITORING
 #endif  // !OS_WIN
@@ skipping 102 matching lines @@
    protected:
     virtual ~PowerObserver() {}
   };
 
   class BASE_EXPORT DevicesChangedObserver {
    public:
     // Notification that the devices connected to the system have changed.
     // This is only implemented on Windows currently.
     virtual void OnDevicesChanged(DeviceType device_type) {}
 
+    // Called when the free space of the storage containing the |path| is
+    // changed.
+    virtual void OnStorageFreeSpaceChanged(const FilePath::StringType& path);
+
     // When a removable storage device is attached or detached, one of these
     // two events is triggered.
     virtual void OnRemovableStorageAttached(
         const std::string& id,
         const string16& name,
         const FilePath::StringType& location) {}
     virtual void OnRemovableStorageDetached(const std::string& id) {}
 
    protected:
     virtual ~DevicesChangedObserver() {}
@@ skipping 21 matching lines @@
   // Cross-platform handling of a power event.
   void ProcessPowerMessage(PowerEvent event_id);
 
   // Cross-platform handling of a device change event.
   void ProcessDevicesChanged(DeviceType device_type);
   void ProcessRemovableStorageAttached(const std::string& id,
                                        const string16& name,
                                        const FilePath::StringType& location);
   void ProcessRemovableStorageDetached(const std::string& id);
 
+  // Start watching the storage device containing the |path| for its free
+  // space changes. The |path| can be a drive name on Windows, or a device
+  // name on Linux. Return true if succeeds to start watching.
+  bool StartWatchStorageDevice(const FilePath::StringType& path);

[vandebo (ex-Chrome), 2012/08/28 23:56:30]

nit: Watch -> Watching

+  // Stop watching the storage device containing the |path|.
+  bool StopWatchStorageDevice(const FilePath::StringType& path);
+
  private:
   // Mapping of unique device id to device info tuple.
   typedef std::map<std::string, RemovableStorageInfo> RemovableStorageMap;
+  // Mapping of the storage path to watcher.
+  typedef std::map<FilePath::StringType,
+    scoped_refptr<FilePathWatcher::PlatformDelegate> > StorageDeviceWatcherMap;
 
 #if defined(OS_MACOSX)
   void PlatformInit();
   void PlatformDestroy();
 #endif
 
   // Platform-specific method to check whether the system is currently
   // running on battery power.  Returns true if running on batteries,
   // false otherwise.
   bool IsBatteryPower();
 
   // Checks the battery status and notifies observers if the battery
   // status has changed.
   void BatteryCheck();
 
   // Functions to trigger notifications.
   void NotifyDevicesChanged(DeviceType device_type);
+  void NotifyStorageFreeSpaceChanged(const FilePath::StringType& path,
+                                     double available_capacity);
   void NotifyRemovableStorageAttached(const std::string& id,
                                       const string16& name,
                                       const FilePath::StringType& location);
   void NotifyRemovableStorageDetached(const std::string& id);
   void NotifyPowerStateChange();
   void NotifySuspend();
   void NotifyResume();
 
   scoped_refptr<ObserverListThreadSafe<PowerObserver> > power_observer_list_;
   scoped_refptr<ObserverListThreadSafe<DevicesChangedObserver> >
       devices_changed_observer_list_;
   bool battery_in_use_;
   bool suspended_;
 
 #if defined(ENABLE_BATTERY_MONITORING)
   base::OneShotTimer<SystemMonitor> delayed_battery_check_;
 #endif
 
 #if defined(OS_IOS)
   // Holds pointers to system event notification observers.
   std::vector<id> notification_observers_;
 #endif
 
   // Map of all the attached removable storage devices.
   RemovableStorageMap removable_storage_map_;
 
+  // Map of all storage watchers.
+  StorageDeviceWatcherMap storage_watcher_map_;
+
   DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
 };
 
 }  // namespace base
 
 #endif  // BASE_SYSTEM_MONITOR_SYSTEM_MONITOR_H_