Fix latency info tracking for coalesced events.

ui/events/blink/blink_event_util.cc

Index: ui/events/blink/blink_event_util.cc
diff --git a/ui/events/blink/blink_event_util.cc b/ui/events/blink/blink_event_util.cc
index 6d9cccee98225a441da08ea4936360fa307167e1..7b3ee486d99c2ca2ac9c1dcbc73b9abfa6c64597 100644
--- a/ui/events/blink/blink_event_util.cc
+++ b/ui/events/blink/blink_event_util.cc
@@ -343,6 +343,7 @@ void Coalesce(const WebTouchEvent& event_to_coalesce, WebTouchEvent* event) {
   event->moved_beyond_slop_region |= old_event.moved_beyond_slop_region;
   event->dispatch_type = MergeDispatchTypes(old_event.dispatch_type,
                                             event_to_coalesce.dispatch_type);
+  event->unique_touch_event_id = old_event.unique_touch_event_id;
 }
 
 bool CanCoalesce(const WebGestureEvent& event_to_coalesce,