mus-ws: Plumb FrameSinkId to Children

ui/views/test/native_widget_factory_aura_mus.cc

Index: ui/views/test/native_widget_factory_aura_mus.cc
diff --git a/ui/views/test/native_widget_factory_aura_mus.cc b/ui/views/test/native_widget_factory_aura_mus.cc
index faa7fd6aac4e42ae7e09b62539fc397cf992f0cc..292e7a939e1e19f12b15f2ba9f8de7fb52dc4e2b 100644
--- a/ui/views/test/native_widget_factory_aura_mus.cc
+++ b/ui/views/test/native_widget_factory_aura_mus.cc
@@ -32,7 +32,8 @@ NativeWidget* CreatePlatformNativeWidgetImplAuraMus(
       MusClient::Get()->ConfigurePropertiesFromParams(init_params);
   desktop_native_widget_aura->SetDesktopWindowTreeHost(
       base::MakeUnique<DesktopWindowTreeHostMus>(
-          widget, desktop_native_widget_aura, &mus_properties));
+          widget, desktop_native_widget_aura, cc::FrameSinkId(),
+          &mus_properties));
   return desktop_native_widget_aura;
 }