Expose native, desktop and mobile gesture detection defaults

ui/aura/window_event_dispatcher.cc

Index: ui/aura/window_event_dispatcher.cc
diff --git a/ui/aura/window_event_dispatcher.cc b/ui/aura/window_event_dispatcher.cc
index 3313d137bca352262566c28ebc10e114f02732d5..b4077ffe79bfbfc62c5f48b6e76f2f41d8af1d7d 100644
--- a/ui/aura/window_event_dispatcher.cc
+++ b/ui/aura/window_event_dispatcher.cc
@@ -883,7 +883,7 @@ void WindowEventDispatcher::PreDispatchTouchEvent(Window* target,
   }
 
   ui::TouchEvent orig_event(*event, target, window());
-  if (!ui::GestureRecognizer::Get()->ProcessTouchEventPreDispatch(orig_event,
+  if (!ui::GestureRecognizer::Get()->ProcessTouchEventPreDispatch(&orig_event,
                                                                   target)) {
     // The event is invalid - ignore it.
     event->StopPropagation();
@@ -891,6 +891,10 @@ void WindowEventDispatcher::PreDispatchTouchEvent(Window* target,
     return;
   }
 
+  // This flag is set depending on the gestures recognized in the call above,
+  // and needs to propagate with the forwarded event.
+  event->set_may_cause_scrolling(orig_event.may_cause_scrolling());
+

[sadrul, 2014/12/15 17:40:46]

Can you add a test to make sure this bit is set correctly in the correct event?
(e.g. generate a touch-press event, then a touch-move with enough delta to make
sure this gets set, and verify that this indeed gets set).

[jdduke (slow), 2014/12/15 18:37:37]

Done.

   PreDispatchLocatedEvent(target, event);
 }