I used a git wrapper for google3 repo. It wasn't great. There are a number of semantic differences between piper/perforce and git that made it awkward. Especially code review- git doesn't handle code review well (I still find this to be an issue with github and other sites that have code review). but it was not an officially supported solution and I believe the replacement for it is based on another DVCS, Mercurial, for some silly software engineering reasons I don't like.