Extend system monitor capacity for watching the free space changes

base/system_monitor/system_monitor.cc

Index: base/system_monitor/system_monitor.cc
diff --git a/base/system_monitor/system_monitor.cc b/base/system_monitor/system_monitor.cc
index 3a3aded459e2eb7ebbe72a0b7b6172c1a82be390..7822ece94ae07e205e7d73085a73915866ecc708 100644
--- a/base/system_monitor/system_monitor.cc
+++ b/base/system_monitor/system_monitor.cc
@@ -151,6 +151,15 @@ void SystemMonitor::NotifyDevicesChanged(DeviceType device_type) {
       &DevicesChangedObserver::OnDevicesChanged, device_type);
 }
 
+void SystemMonitor::NotifyStorageFreeSpaceChanged(
+    const FilePath::StringType& path, double available_capacity) {
+  DVLOG(1) << "StorageFreeSpaceChanged with path " << path
+           << " and free space " << available_capacity;
+  devices_changed_observer_list_->Notify(
+      &DevicesChangedObserver::OnStorageFreeSpaceChanged,
+      path, available_capacity);
+}
+
 void SystemMonitor::NotifyRemovableStorageAttached(
     const std::string& id,
     const string16& name,