Extend system monitor capacity for watching the free space changes

base/system_monitor/system_monitor.h

Index: base/system_monitor/system_monitor.h
diff --git a/base/system_monitor/system_monitor.h b/base/system_monitor/system_monitor.h
index 3a48e3a9cff6a9302319aae9ee8409ad503ec51e..4d0832635202ffe5097f7ce6099cb47ee245c560 100644
--- a/base/system_monitor/system_monitor.h
+++ b/base/system_monitor/system_monitor.h
@@ -12,6 +12,7 @@
 #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"
 
@@ -134,6 +135,10 @@ class BASE_EXPORT SystemMonitor {
     // 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(
@@ -175,9 +180,19 @@ class BASE_EXPORT SystemMonitor {
                                        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();
@@ -195,6 +210,8 @@ class BASE_EXPORT SystemMonitor {
 
   // 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);
@@ -221,6 +238,9 @@ class BASE_EXPORT SystemMonitor {
   // 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);
 };