StructTraits to map mus::mojom::Event to unique_ptr<ui::Event>

ash/mus/window_manager_application.cc

Index: ash/mus/window_manager_application.cc
diff --git a/ash/mus/window_manager_application.cc b/ash/mus/window_manager_application.cc
index 472cd79ea461c3e815bc2938a27d9ada1ebe35ea..21129f9fc077888f34cce83cc195411e759e3413 100644
--- a/ash/mus/window_manager_application.cc
+++ b/ash/mus/window_manager_application.cc
@@ -101,7 +101,7 @@ void WindowManagerApplication::OnAccelerator(uint32_t id,
                                              const ui::Event& event) {
   for (auto* registrar : accelerator_registrars_) {
     if (registrar->OwnsAccelerator(id)) {
-      registrar->ProcessAccelerator(id, ::mus::mojom::Event::From(event));
+      registrar->ProcessAccelerator(id, event);
       break;
     }
   }