I've come to this cafe a few times. It's Joy's Place on Post St. in the Tenderloin/Tendernob. I think I've also seen the victim of the theft there a few times (working in XCode). Probably not the first time she's left her stuff and used the bathroom; assuming she felt the cafe was a safe/trusted place to leave items unattended.

In other thoughts: the thief pulls the ultimate scumbag move and asks for someone to watch her purse whilst she uses the bathroom. Then steals from someone else in the bathroom. Always keep your valuables attended!