Fully support the autohide shelf option for touch UI on Windows.

ash/wm/system_gesture_event_filter.h

Index: ash/wm/system_gesture_event_filter.h
diff --git a/ash/wm/system_gesture_event_filter.h b/ash/wm/system_gesture_event_filter.h
index bc57b7c9dcf3972524509cb557abafcc8ebc8f01..a8ec4e2be25c573cc8ba6591066b1ced49abfc10 100644
--- a/ash/wm/system_gesture_event_filter.h
+++ b/ash/wm/system_gesture_event_filter.h
@@ -31,6 +31,7 @@ class SystemGestureEventFilterTest;
 namespace internal {
 class LongPressAffordanceHandler;
 class OverviewGestureHandler;
+class ShelfGestureHandler;
 class SystemPinchHandler;
 class TouchUMA;
 
@@ -67,6 +68,7 @@ class SystemGestureEventFilter : public ui::EventHandler,
 
   scoped_ptr<LongPressAffordanceHandler> long_press_affordance_;
   scoped_ptr<OverviewGestureHandler> overview_gesture_handler_;
+  scoped_ptr<ShelfGestureHandler> shelf_gesture_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemGestureEventFilter);
 };