The certificate authority and server certificates here are generated by $topsrcdir/build/pgo/genpgocert.py.

You can generate a new CA cert by running:
./mach python build/pgo/genpgocert.py --gen-ca

You can generate new server certificates by running:
./mach python build/pgo/genpgocert.py --gen-server

These commands will modify cert8.db and key3.db. The changes to these should be committed.
