Changes to QUIC are initially committed to the Chromium repository. Roughly once a week a Google developer will bundle up recent changes in Chromium's QUIC code and add them to this repository (proto-quic).
To contribute code changes to proto-quic you should submit patches upstream to Chromium.
For non-code changes, any contributors must sign the google CLA (https://cla.developers.google.com/clas) before sending pull requests to proto-quic.