GitLab

- Rename Init as Start.
- Rename CreateSubsystems as Init.

As a result, Init is truely the first thing that must be called before using the
instance.

Bug: 920062
Change-Id: I5606250f10c3d249a994f19b71682a8d95e44be0
Reviewed-on: https://chromium-review.googlesource.com/c/1442072Reviewed-by: Alan Cutter <alancutter@chromium.org>
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626911}