Currently the pre-cq-launcher (and the master-paladin builder) perform repo sync's then cherry-pick CLs in locally to see if the CLs will apply cleanly against a ChromeOS checkout.

This means knowing if they apply against a repo which is currently part of ChromeOS, as well as knowing if they apply cleanly.

If we could tell if they will apply cleanly via Gerrit API, they would not need to sync the general ChromeOS code (and the launcher would not need to do so in a loop).

This would help with GoB quota problems, GoB flake, and if an API solution could be found, it would be very helpful when/if we replace the pre-cq-launcher with a service.