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

ui/events/gesture_detection/gesture_event_data.cc

Index: ui/events/gesture_detection/gesture_event_data.cc
diff --git a/ui/events/gesture_detection/gesture_event_data.cc b/ui/events/gesture_detection/gesture_event_data.cc
index 8750c248e0edfb2f6cb7d5a4671d9c035e3f15bf..0177d9655746e3a1f1ff51212b9721292dbb59fa 100644
--- a/ui/events/gesture_detection/gesture_event_data.cc
+++ b/ui/events/gesture_detection/gesture_event_data.cc
@@ -13,6 +13,7 @@ GestureEventData::GestureEventData(EventType type,
                                    base::TimeTicks time,
                                    float x,
                                    float y,
+                                   int touch_point_count,
                                    const GestureEventDetails& details)
     : type(type),
       motion_event_id(motion_event_id),
@@ -21,14 +22,17 @@ GestureEventData::GestureEventData(EventType type,
       y(y),
       details(details) {
   DCHECK(motion_event_id >= 0);
+  DCHECK_NE(0, touch_point_count);
   DCHECK(ET_GESTURE_TYPE_START <= type && type <= ET_GESTURE_TYPE_END);
+  this->details.set_touch_points(touch_point_count);
 }
 
 GestureEventData::GestureEventData(EventType type,
                                    int motion_event_id,
                                    base::TimeTicks time,
                                    float x,
-                                   float y)
+                                   float y,
+                                   int touch_point_count)
     : type(type),
       motion_event_id(motion_event_id),
       time(time),
@@ -36,7 +40,9 @@ GestureEventData::GestureEventData(EventType type,
       y(y),
       details(GestureEventDetails(type, 0, 0)) {
   DCHECK(motion_event_id >= 0);
+  DCHECK_NE(0, touch_point_count);
   DCHECK(ET_GESTURE_TYPE_START <= type && type <= ET_GESTURE_TYPE_END);
+  details.set_touch_points(touch_point_count);
 }
 
 GestureEventData::GestureEventData() : type(ET_UNKNOWN), x(0), y(0) {}