I don't think that's on Google. I tried it last time using git. Having learned more about git: the defaults are not well suited to large repos. Worse: it's not easy to get the right settings.
Why would they do that? Chrome being hard to compile is a benefit to them. It means it's harder for people to fragment the Chrome ecosystem by making slightly-incompatible forks.
And my recollection is that Google devs use something akin to Chromebooks, coding remotely, meaning the multi-gigabyte repo isn't on "their machine" anyway