How can I compare code reviews against git repository for completeness?

We want to make sure we've reviewed all of our code, and have reviewed the most recent versions of all of our code.  What I'm imagining, is looking through all of the files in our git repository, and making sure there are matching code reviews in collaborator.

Is there anything in any of the tools that would help me do this?  A GUI, a command line tool, a JSON API - anything that would list the git hash values of each of the files that I've reviewed?

Thanks,

Chris