Set the unique_event_id when converting from TouchEvent to WebTouchEvent

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 835a82b243640998d7c35ad7a64114c2800d440c..c4bf7707351dfa2bc8d914c4a6a545a1418ac4ff 100644
--- a/ui/events/blink/blink_event_util.cc
+++ b/ui/events/blink/blink_event_util.cc
@@ -142,6 +142,7 @@ blink::WebTouchEvent CreateWebTouchEventFromMotionEvent(
       (event.GetEventTime() - base::TimeTicks()).InSecondsF(),
   result.causesScrollingIfUncanceled = may_cause_scrolling;
   result.modifiers = EventFlagsToWebEventModifiers(event.GetFlags());
+  result.uniqueTouchEventId = event.GetUniqueId();
   result.touchesLength =
       std::min(static_cast<unsigned>(event.GetPointerCount()),
                static_cast<unsigned>(WebTouchEvent::touchesLengthCap));