Don't pass touches to gesture recognizer for async acks.

ui/aura/window_tree_host.h

Index: ui/aura/window_tree_host.h
diff --git a/ui/aura/window_tree_host.h b/ui/aura/window_tree_host.h
index b08391ffcf6ac3d44bdd5085c7c44b2e5699655c..34f7c7ad3653501cdf1dd250b4c30b7ff8b39326 100644
--- a/ui/aura/window_tree_host.h
+++ b/ui/aura/window_tree_host.h
@@ -66,7 +66,6 @@ class AURA_EXPORT WindowTreeHost {
     return const_cast<WindowEventDispatcher*>(
         const_cast<const WindowTreeHost*>(this)->dispatcher());
   }
-  const WindowEventDispatcher* dispatcher() const { return dispatcher_.get(); }
 
   ui::Compositor* compositor() { return compositor_.get(); }
 
@@ -182,7 +181,7 @@ class AURA_EXPORT WindowTreeHost {
 
   ObserverList<WindowTreeHostObserver> observers_;
 
-  scoped_ptr<WindowEventDispatcher> dispatcher_;
+  const WindowEventDispatcher* dispatcher() const { return dispatcher_.get(); }
 
   scoped_ptr<ui::Compositor> compositor_;
 
@@ -191,6 +190,7 @@ class AURA_EXPORT WindowTreeHost {
   gfx::Point last_cursor_request_position_in_host_;
 
   scoped_ptr<ui::ViewProp> prop_;
+  scoped_ptr<WindowEventDispatcher> dispatcher_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeHost);
 };