Change ui cursor identifiers to an enum class.

ash/display/cursor_window_controller.h

Index: ash/display/cursor_window_controller.h
diff --git a/ash/display/cursor_window_controller.h b/ash/display/cursor_window_controller.h
index 8cf4736dd1e84c56a84424472cf811b7d684734b..b81638037ee4e85c56a3c41cdd5f384308b224a2 100644
--- a/ash/display/cursor_window_controller.h
+++ b/ash/display/cursor_window_controller.h
@@ -79,7 +79,7 @@ class ASH_EXPORT CursorWindowController {
   gfx::Rect bounds_in_screen_;
 
   // The native_type of the cursor, see definitions in cursor.h
-  int cursor_type_;
+  ui::CursorType cursor_type_;
 
   // The last requested cursor visibility.
   bool visible_;