Explicitly initialize dbus in ash

While mash was in early development we supported a number of different
inititialization paths. That has since been simplified, we should now
explicitly initialize dbus from the correct places.

Bug: 647367
Change-Id: If5ec193ffe2a8db03bf1ddfe756815fb806d8b06
Reviewed-on: https://chromium-review.googlesource.com/c/1490400
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636182}
4 files changed