Change OnWindowInputEvent to use display_id to find the host and update event root_location in WS.

services/ui/ws/test_change_tracker.h

Index: services/ui/ws/test_change_tracker.h
diff --git a/services/ui/ws/test_change_tracker.h b/services/ui/ws/test_change_tracker.h
index 3421441e176176f57baa3e9ee5af7a6ac8b925df..8cb0a7839357b7ff3e95054e888848dc048de2c4 100644
--- a/services/ui/ws/test_change_tracker.h
+++ b/services/ui/ws/test_change_tracker.h
@@ -80,6 +80,7 @@ struct Change {
   base::Optional<cc::LocalSurfaceId> local_surface_id;
   int32_t event_action;
   bool matches_pointer_watcher;
+  gfx::Point event_root_location;
   std::string embed_url;
   mojom::OrderDirection direction;
   bool bool_value;