Change factory related build logic to use virtual/target-os-factory{-shim}.

The new target-os-factory and target-os-factory-shim packages provide a
simpler way to manage factory related packages so we don't need to
hard-code and list individual package names any more.

The make_factory_toolkit script is still using explicit package list
because it's merging packages without dependency and should be revised
in future.

BUG=chromium:577601
TEST=build_packages; build_image factory factory_install
CQ-DEPEND=CL:322072

Change-Id: I65e711a5fb168d3c266de03921431df7c186258d
Reviewed-on: https://chromium-review.googlesource.com/322042
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
3 files changed