GitLab

The master-only directory has been unwieldy and in order to support LTS
an additional subset would be required which would make doing it by
directory even more unwieldy. The addition of a library for
conditionally defining LUCI resources depending on the branch means that
the builders for a bucket can be located together and the
branch_selector value controls which branches they are actually defined
for.

Bug: 1119446
Change-Id: I1dff1f8e6c0485e31fd902c383f02b37a3f0d138
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2378794Reviewed-by: Erik Staab <estaab@chromium.org>
Commit-Queue: Garrett Beaty <gbeaty@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802046}