Gray is in processing mode, I'm also surprised he thought to take pictures of the visible proof of his assault. After the showers, any physical evidence is gone, but if someone else reports Shane (I have no doubt he has done this before and will do it again), Gray may be able to corroborate their claim. He needs a friend to talk to, he feels alone.
Regarding the "chips and gravy", I think this is fries and gravy. Australians call ketchup "sauce", so I think gravy is gravy, like Canadians have fries with cheese and gravy (poutine).