[endorphone]

Google has never been required to commit upstream, but they've chosen to do so because of the ease of integrating changes downstream. They could have forked off and bashed the code into whatever form they wanted to. Breaking anything and everything.

But they didn't. They kept keeping it in sync. They probably had a reason for doing that.

[pjmlp]

Google has chosen to cherry pick commits to upstream, there is still plenty of stuff on AOSP, and much more on internal Googleplex repos.