buffet: Add libbuffet library and test daemon

Re-organized code in Buffet a bit. Moved dbus_constants into
libbuffet, so they can be used by both buffet and outside parties.

Added libbuffet shared library and thin helper classes to listen
to command update notifications from buffet daemon and let consumers
handle new commands by providing a simple callback.

Added a very simple test daemon to illustrate how to implement
a daemon that would respond to Buffet commands. test_daemon is
being built but is not installed into the image right now...

BUG=chromium:412583
TEST=Buffet compiles and unit tests run
CQ-DEPEND=CL:217838

Change-Id: Ica025bfdb7fc439c58c662ef3a015abc12426806
Reviewed-on: https://chromium-review.googlesource.com/217890
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
20 files changed
tree: 212b10bffafdf8a5d3b14ad5c5f7c5e972395927
  1. buffet/