ui::GestureProvider gives GestureEventData the number of touch points.

ui/events/gesture_detection/touch_disposition_gesture_filter.cc

Index: ui/events/gesture_detection/touch_disposition_gesture_filter.cc
diff --git a/ui/events/gesture_detection/touch_disposition_gesture_filter.cc b/ui/events/gesture_detection/touch_disposition_gesture_filter.cc
index 6f405e58f96faa00f18fbe1fe1c62c8ae17bcbf5..dc92250e99a04c9c5679db530c9ae0467185926d 100644
--- a/ui/events/gesture_detection/touch_disposition_gesture_filter.cc
+++ b/ui/events/gesture_detection/touch_disposition_gesture_filter.cc
@@ -15,12 +15,14 @@ namespace {
 COMPILE_ASSERT(ET_GESTURE_TYPE_END - ET_GESTURE_TYPE_START < 32,
                gesture_type_count_too_large);
 
-GestureEventData CreateGesture(EventType type, int motion_event_id) {
+GestureEventData CreateGesture(EventType type,
+                               int motion_event_id) {
   return GestureEventData(type,
                           motion_event_id,
                           base::TimeTicks(),
                           0,
                           0,
+                          1,
                           GestureEventDetails(type, 0, 0));
 }