Code review comment for lp:~unity-team/unity/unity-sru-fix-mem-leaks

1. We could remove the layout member variable if it is not a problem for the SRU (change in the .h file)
2. You don't need to call SinkReference on the panelController because it does not have a floating reference. Only objects that inherit from Nux::InitiallyUnownedObject have a floating reference. In Nux, widgets (see Nux::Area) have a floating reference. Calling SinkReference on panelController will do nothing.