Expose native, desktop and mobile gesture detection defaults

ui/aura/window_event_dispatcher.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/window_event_dispatcher.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 865 matching lines @@
         return;
       }
       break;
 
     default:
       NOTREACHED();
       break;
   }
 
   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();
     event->DisableSynchronousHandling();
     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);
 }
 
 }  // namespace aura