[Ozone] Check valid GetFlingData parameters before writing to them

ui/events/ozone/events_ozone.cc

Index: ui/events/ozone/events_ozone.cc
diff --git a/ui/events/ozone/events_ozone.cc b/ui/events/ozone/events_ozone.cc
index d5d75afe849a295a834c8b2a747277eac6dc851e..65ad063dde3525431ba51a24c5e1735c7d359e34 100644
--- a/ui/events/ozone/events_ozone.cc
+++ b/ui/events/ozone/events_ozone.cc
@@ -144,11 +144,17 @@ bool GetFlingData(const base::NativeEvent& native_event,
   const ui::ScrollEvent* event =
       static_cast<const ui::ScrollEvent*>(native_event);
   DCHECK(event->IsScrollEvent());
-  *vx = event->x_offset();
-  *vy = event->y_offset();
-  *vx_ordinal = event->x_offset_ordinal();
-  *vy_ordinal = event->y_offset_ordinal();
-  *is_cancel = event->type() == ET_SCROLL_FLING_CANCEL;
+  if (vx)
+    *vx = event->x_offset();
+  if (vy)
+    *vy = event->y_offset();
+  if (vx_ordinal)
+    *vx_ordinal = event->x_offset_ordinal();
+  if (vy_ordinal)
+    *vy_ordinal = event->y_offset_ordinal();
+  if (is_cancel)
+    *is_cancel = event->type() == ET_SCROLL_FLING_CANCEL;
+
   return true;
 }