Add script that adds depot_tools and chromite/bin to the PATH globally using /etc/env.d
BUG=16093
TEST=Ran make_chroot and run_chroot_version_hooks
Change-Id: I6011d7436f18ce46dfe215f01068e862d2567273
Reviewed-on: http://gerrit.chromium.org/gerrit/2022
Reviewed-by: David James <davidjames@chromium.org>
Tested-by: Ryan Cui <rcui@chromium.org>