That was my initial thought. However, assuming that the photo is real, Westinghouse could have had the project to design and build the gas chamber itself.
Which makes me wonder even more: what is this picture really showing? Was it staged by someone with a Westinghouse-satirizing or -critical perspective? (Might the modern equivalent be a Tesla logo, especially if there are ever any fatalities due to a battery/charging problem?)
It could be a leftover hood from the electric chair. I imagine it's more important to cover the face of someone being electrocuted to death than being gassed, at least from the observer's standpoint.