The Foundation owns the Corporation, so technically the Corporation answers to the Foundation, but because the Foundation is a non-profit it can't actually transfer resources to its for-profit arm, only the other way around.

Usually the theory with this kind of setup is that the Corporation is profitable and forwards funds to the Foundation so that the foundation can accomplish its work. But putting Firefox in the Foundation implies that someone somewhere thought that Firefox would be profitable rather than being the core mission that needs subsidization. I believe this was someone related to the Google deal, but it's definitely been a major problem ever since.