cros: Default to natural scrolling if the internal diplay is a touchscreen.

ui/events/event_utils.h

Index: ui/events/event_utils.h
diff --git a/ui/events/event_utils.h b/ui/events/event_utils.h
index bcf1213855ea9675b0954edd62aedc4bd9fc8fc3..be210e6851508e3d74004423b073819e098a4439 100644
--- a/ui/events/event_utils.h
+++ b/ui/events/event_utils.h
@@ -124,6 +124,9 @@ EVENTS_EXPORT void SetNaturalScroll(bool enabled);
 // In natural scrolling enabled for touchpads?
 EVENTS_EXPORT bool IsNaturalScrollEnabled();
 
+// Returns whether natural scrolling should be used for touchpad.
+EVENTS_EXPORT bool ShouldDefaultToNaturalScroll();
+
 // Was this event generated by a touchpad device?
 // The caller is responsible for ensuring that this is a mouse/touchpad event
 // before calling this function.