Mash cleanup: Remove power manager mojo interface and impl

Bug: 958089

Change-Id: If1eb44243dd79533f3e6eacd1ed81a748d271548
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1589832
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Auto-Submit: Evan Stade <estade@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#655524}
29 files changed