Make RootView::DispatchGestureEvent() non-virtual

ui/events/event.h

Index: ui/events/event.h
diff --git a/ui/events/event.h b/ui/events/event.h
index 2988d471b11c1060fc2a49a896d672d52babce44..1119e36f41335aea2cbcbe95de30a3969881a851 100644
--- a/ui/events/event.h
+++ b/ui/events/event.h
@@ -184,6 +184,11 @@ class EVENTS_EXPORT Event {
     return type_ == ET_MOUSEWHEEL;
   }
 
+  // Convenience methods to cast |this| to a GestureEvent. IsGestureEvent()
+  // must be true as a precondition to calling these methods.
+  GestureEvent* AsGestureEvent();
+  const GestureEvent* AsGestureEvent() const;
+
   // Returns true if the event has a valid |native_event_|.
   bool HasNativeEvent() const;