I did mention how Android used a homemade tool to do the reviews. It was introduced to me by a friend who is doing Android development for mobile phone companies. At first I was like: what about the existing google code or github? Then he explained me their pre commit workflow and it made me sure we wanted to use that. I think Ryan met the OpenStack folks who are using Gerrit. That probably convinced him it was the right tool for us too.
Actually, we started using Gerrit for Ops before OpenStack switched to it. It's just a happy coincidence.
- Ryan