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

ui/events/gestures/gesture_recognizer_impl_mac.cc

Index: ui/events/gestures/gesture_recognizer_impl_mac.cc
diff --git a/ui/events/gestures/gesture_recognizer_impl_mac.cc b/ui/events/gestures/gesture_recognizer_impl_mac.cc
index 3a80e5d4c35882a56b5db4debc6f171484070731..fac793598c9735336b2a52739c805a3f48b63245 100644
--- a/ui/events/gestures/gesture_recognizer_impl_mac.cc
+++ b/ui/events/gestures/gesture_recognizer_impl_mac.cc
@@ -22,8 +22,7 @@ class GestureRecognizerImplMac : public GestureRecognizer {
     return false;
   }
 
-  Gestures* AckAsyncTouchEvent(const TouchEvent& event,
-                               ui::EventResult result,
+  Gestures* AckAsyncTouchEvent(ui::EventResult result,
                                GestureConsumer* consumer) override {
     return NULL;
   }