Reland "Mac: exit browser fullscreen on Esc"

This reverts commit 130b6251b507d2a9c7f28d8df401c0e90382228a.

Reason for revert: Fixed in patchset 2

Original change's description:
> Revert "Mac: exit browser fullscreen on Esc"
>
> This reverts commit a9f47ca0075744e7dc10d14c96d4611bf3592ab5.
>
> Reason for revert: https://crbug.com/1077651
>
> Original change's description:
> > Mac: exit browser fullscreen on Esc
> >
> > Every (non-Chrome) Mac app I've tried supports this, and nobody seems to
> > know of a good reason for why we don't do it, so let's do it.
> >
> > Bug: 1074609
> > Change-Id: I43e9b5137faf347e17e737e2e3f2cbdba4e6c470
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2174345
> > Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
> > Commit-Queue: Leonard Grey <lgrey@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#764644}
>
> TBR=ellyjones@chromium.org,lgrey@chromium.org
>
> # Not skipping CQ checks because original CL landed > 1 day ago.
>
> Bug: 1074609
> Change-Id: I9825e3f24975563333e35263b22316b3c25a6a88
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2179663
> Reviewed-by: Leonard Grey <lgrey@chromium.org>
> Commit-Queue: Leonard Grey <lgrey@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#765065}

TBR=ellyjones@chromium.org,lgrey@chromium.org

Change-Id: I60a112cc2521a286736cb0186202e79d09567dff
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1074609
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2179765
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Leonard Grey <lgrey@chromium.org>
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#766409}