Revert "Refactor Smart Dim, making it a D-Bus service"

This reverts commit 1b42c60c4c748bc600e1c740b03c87f3aa9cc14d.

Reason for revert: 

Speculative revert for webgl_conformance failures on ChromeOS AMD64 bots:
https://ci.chromium.org/p/chromium/builders/ci/chromeos-amd64-generic-rel/31288

BUG=977958,977881,977850,977913,977830

Original change's description:
> Refactor Smart Dim, making it a D-Bus service
> 
> Add a Chrome D-Bus service, export ShouldDeferScreenDim method for
> powerd to call
> 
> Bug: 933199
> Change-Id: I275f4eb5f406d6ecdd1fca3590a00c2a0618eb4d
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1598921
> Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
> Reviewed-by: Mattias Nissler <mnissler@chromium.org>
> Reviewed-by: Dan Erat <derat@chromium.org>
> Reviewed-by: Andrew Moylan <amoylan@chromium.org>
> Commit-Queue: Xinglong Luan <alanlxl@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#671533}

TBR=derat@chromium.org,stevenjb@chromium.org,mnissler@chromium.org,amoylan@chromium.org,jiameng@chromium.org,alanlxl@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 933199
Change-Id: Idaefb41c5150aed3bfae8ab043c8e11fbe062463
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1674444
Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Dan Beam <dbeam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671776}
18 files changed