mus: Fix event transformation in client code.

ui/events/event.cc

Index: ui/events/event.cc
diff --git a/ui/events/event.cc b/ui/events/event.cc
index 7753a8af74eac39b3dbc73dafb8510df33a8949d..6541415d9524065c674e3516fc65d807e906f21f 100644
--- a/ui/events/event.cc
+++ b/ui/events/event.cc
@@ -444,10 +444,20 @@ LocatedEvent::LocatedEvent(EventType type,
 void LocatedEvent::UpdateForRootTransform(
     const gfx::Transform& reversed_root_transform) {
   // Transform has to be done at root level.
+  bool locations_equal = location_ == root_location_;
   gfx::Point3F p(location_);
   reversed_root_transform.TransformPoint(&p);
   location_ = p.AsPointF();
-  root_location_ = location_;
+  if (locations_equal) {
+    root_location_ = location_;
+    LOG(ERROR) << name() << " Set to " << root_location_.ToString();
+  } else {
+    p = gfx::Point3F(root_location_);
+    reversed_root_transform.TransformPoint(&p);
+    root_location_ = p.AsPointF();
+    LOG(ERROR) << name() << " Set to " << root_location_.ToString()
+               << " instead of " << location_.ToString();
+  }
 }
 
 ////////////////////////////////////////////////////////////////////////////////