Previously, in most cases when ARC session is restarted, Chrome is crashed as well and so ArcKioskAppService state is re-initialized.
However, if it's not re-created, it won't start the app.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9dd91389e9807b53ddbf5ebe60d476448f113840

commit 9dd91389e9807b53ddbf5ebe60d476448f113840
Author: Sergey Poromov <poromov@chromium.org>
Date: Mon Apr 09 21:23:20 2018

arc: Reset kiosk state when ARC session is closed/restarted.

When ARC session is restarted or closed, OnTaskDestroyed()
callback is not necessary send for all apps. Because of that
ArcKioskAppService continued to think that kiosk app is still running,
while it's not true.
Perfectly, instead of |if (!app_launcher_)| check in line 193,
it should check whether kiosk app is already running (and update taskid)
but there is no such function, so just re-setting internal state
on restart/close should work too.

BUG= 830640 

Change-Id: I8097e03000d0d9e21b672672cddaf3a91a1d3214
Reviewed-on: https://chromium-review.googlesource.com/1000455
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Yury Khmel <khmel@chromium.org>
Commit-Queue: Sergey Poromov <poromov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549280}
[modify] https://crrev.com/9dd91389e9807b53ddbf5ebe60d476448f113840/chrome/browser/chromeos/app_mode/arc/arc_kiosk_app_service.cc
[modify] https://crrev.com/9dd91389e9807b53ddbf5ebe60d476448f113840/chrome/browser/chromeos/app_mode/arc/arc_kiosk_app_service.h

Requesting merge into M66 if not too late.
The change affects only ARC Kiosk sessions.

This bug requires manual review: We are only 7 days from stable.
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), josafat@(ChromeOS), abdulsyed@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Is it approved for M67 or M66?

Sorry typo, approved for M66 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d0017151ab55a574d292dae8fa63369dcb76c0ed

commit d0017151ab55a574d292dae8fa63369dcb76c0ed
Author: Sergey Poromov <poromov@chromium.org>
Date: Tue Apr 10 00:00:40 2018

arc: Reset kiosk state when ARC session is closed/restarted.

When ARC session is restarted or closed, OnTaskDestroyed()
callback is not necessary send for all apps. Because of that
ArcKioskAppService continued to think that kiosk app is still running,
while it's not true.
Perfectly, instead of |if (!app_launcher_)| check in line 193,
it should check whether kiosk app is already running (and update taskid)
but there is no such function, so just re-setting internal state
on restart/close should work too.

BUG= 830640 

Change-Id: I8097e03000d0d9e21b672672cddaf3a91a1d3214
Reviewed-on: https://chromium-review.googlesource.com/1000455
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Yury Khmel <khmel@chromium.org>
Commit-Queue: Sergey Poromov <poromov@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#549280}(cherry picked from commit 9dd91389e9807b53ddbf5ebe60d476448f113840)
Reviewed-on: https://chromium-review.googlesource.com/1003672
Reviewed-by: Sergey Poromov <poromov@chromium.org>
Cr-Commit-Position: refs/branch-heads/3359@{#636}
Cr-Branched-From: 66afc5e5d10127546cc4b98b9117aff588b5e66b-refs/heads/master@{#540276}
[modify] https://crrev.com/d0017151ab55a574d292dae8fa63369dcb76c0ed/chrome/browser/chromeos/app_mode/arc/arc_kiosk_app_service.cc
[modify] https://crrev.com/d0017151ab55a574d292dae8fa63369dcb76c0ed/chrome/browser/chromeos/app_mode/arc/arc_kiosk_app_service.h