mash: Convert StatusAreaWidgetDelegate to wm common types

ash/wm/gestures/shelf_gesture_handler.h

Index: ash/wm/gestures/shelf_gesture_handler.h
diff --git a/ash/wm/gestures/shelf_gesture_handler.h b/ash/wm/gestures/shelf_gesture_handler.h
index c944a6897d0736bebb525ca859fff2ec91260af0..8a28c5754893a95d78c543ab413d4f0afe393ba4 100644
--- a/ash/wm/gestures/shelf_gesture_handler.h
+++ b/ash/wm/gestures/shelf_gesture_handler.h
@@ -19,6 +19,8 @@ namespace ash {
 
 // This manages gestures on the shelf (e.g. launcher, status tray) that affects
 // the shelf visibility.
+// TODO(jamescook): Consolidate this with ShelfLayoutManager and its notion of
+// drag status.
 class ShelfGestureHandler {
  public:
   ShelfGestureHandler();