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

chrome/browser/system_monitor/removable_device_notifications_linux.h

Index: chrome/browser/system_monitor/removable_device_notifications_linux.h
diff --git a/chrome/browser/system_monitor/removable_device_notifications_linux.h b/chrome/browser/system_monitor/removable_device_notifications_linux.h
index 4f8ea0b3d39ba7c220ba165bf31f78f0c6a0b824..5068c54bfd6ec6e2b1f2068374805bb7f30c09d0 100644
--- a/chrome/browser/system_monitor/removable_device_notifications_linux.h
+++ b/chrome/browser/system_monitor/removable_device_notifications_linux.h
@@ -37,7 +37,8 @@ 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);
@@ -108,6 +109,10 @@ class RemovableDeviceNotificationsLinux
   // 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_;