Revert of Revert of [Mac] Do not let apps keep Chrome alive if shutting down. (patchs...

Revert of Revert of [Mac] Do not let apps keep Chrome alive if shutting down. (patchset #1 id:1 of https://codereview.chromium.org/821483004/)

Reason for revert:
didn't help... relanding

Original issue's description:
> Revert of [Mac] Do not let apps keep Chrome alive if shutting down. (patchset #6 id:100001 of https://codereview.chromium.org/831813003/)
>
> Reason for revert:
> speculative revert to see whether this broke BrowserTabRestoreTest.RecentTabsMenuTabDisposition on mac dbg
>
> Original issue's description:
> > [Mac] Do not let apps keep Chrome alive if shutting down.
> >
> > If the user quits Chrome while Chrome Apps are running, we keep Chrome running
> > in the background and show a notification.
> >
> > When Chrome is terminated because the system is shutting down or the user is
> > logging off, we should make sure Chrome terminates regardless of any running apps.
> >
> > This CL detects whether an [NSApplication terminate:] is due to shutdown or log off
> > by listening for NSWorkspaceWillPowerOffNotification. This notification is only
> > received if Chrome is about to be terminated, i.e. we do not receive the notification
> > if another app prevented shutdown.
> >
> > BUG=442280
> >
> > Committed: https://crrev.com/f60ef51534ed50361020392ed74435cfa7d6e311
> > Cr-Commit-Position: refs/heads/master@{#311215}
>
> TBR=tapted@chromium.org,rsesek@chromium.org,jackhou@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=442280
>
> Committed: https://crrev.com/494f1ea5e8cb9dea6b78cfb812e4e6a5841ab9b6
> Cr-Commit-Position: refs/heads/master@{#311246}

TBR=tapted@chromium.org,rsesek@chromium.org,jackhou@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=442280

Review URL: https://codereview.chromium.org/851713002

Cr-Commit-Position: refs/heads/master@{#311265}