GitLab

(and a few minor git-cl-formats-du-jour + spot fixes to make new
presubmit checks happy)

(and make thread_restrictions.h presubmits only warnings -- I've been
realizing that making migration presubmits error is a bit too aggressive
specifically because it hinders migrations like these and have been
dialing them down, this one was left behind)

This finalizes the structure for base/task as planned @
https://docs.google.com/document/d/1h-FlOeO-27g__JnuRvdJ8KG9G-bmG_zn6zuw7GerFkc/edit
which makes even more sense in a world where post_task.h and
task_traits.h may be used outside the TaskScheduler (ref.
crbug.com/867421).

There is a low-activity time this week in base/task_scheduler per OOOs
so this is as good a time as ever to make this move (and it must happen
before eseckler's work to use TaskTraits outside TaskScheduler).

The move strategy outlined @
https://chromium-review.googlesource.com/c/chromium/src/+/1161179
makes this CL a simple file move from git's point of view without
requiring all users of public headers to be updated in the same large
CL

Also removed a per-file *task_scheduler* rule from base/test/OWNERS as
there are no such files anymore.

Bug: 867421
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I48b219b9f781deab606e2c6349bc03a0c5b701d8
Reviewed-on: https://chromium-review.googlesource.com/1161088
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580788}