Revert of [Mac] Shut down connections to WindowServer before engaging the sandbox...

Revert of [Mac] Shut down connections to WindowServer before engaging the sandbox. (patchset #1 id:20001 of https://codereview.chromium.org/561833006/)

Reason for revert:
Possibly caused blink test failures.

Original issue's description:
> [Mac] Shut down connections to WindowServer before engaging the sandbox.
>
> The connection is only needed during sandbox warmup to initialize the default
> color space. It was formerly needed by scrollbar NSAnimations, but that was
> replaced via https://codereview.chromium.org/529103002/.
>
> A similar CL was landed and reverted:
> https://chromium.googlesource.com/chromium/src.git/+/53ffdf90f4646dbde8df72007fbdc97f3f0220de
>
> BUG=397642, 306348
> TEST=Manually tested on 10.6-10.10.
>
> Committed: https://crrev.com/f3198fb3fc64878b8feb88cfae28ddb7e8bd71ec
> Cr-Commit-Position: refs/heads/master@{#294382}

TBR=jeremy@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=397642, 306348

Review URL: https://codereview.chromium.org/567693002

Cr-Commit-Position: refs/heads/master@{#294421}