Migration procedure restarts from the login screen when it's finished,
hence we have to persist the "migration done" flag in some way.

My plan is to piggyback it with the pref I added for  Bug 699850 
to disable ARC in "migration skipped" session.
For  bug 709893  I'm going to change the profile pref to local state pref,
so taking the opportunity, the plan is to change the boolean pref to tri-value pref:
{NOT-MIGRATED, MIGRATED, MIGRATED-AND-NOTIFIED}.

"MIGRATED" session can display the toast, only if !profile->IsNewProfile(),
and follow the transition to MIGRATED-AND-NOTIFIED.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6ea2f510147f3bca05aea7024752e95dcf559912

commit 6ea2f510147f3bca05aea7024752e95dcf559912
Author: kinaba <kinaba@chromium.org>
Date: Fri Apr 14 07:24:38 2017

arc: kArcCompatibleFilesystemChosen pref to local state and integer.

For  bug 709893 ,
It needs to be established before profile's KeyedService starts working,
hence is moved to the local state which can be initialized earlier.

For  bug 711095 ,
to implement a one-time UI to show the success of navigation to the user,
this value needs to be tri-state (notyet, done, done-and-notified).
Taking this opportunity to move to local state, this CL changes the type
of the pref from boolean to integer as well.

BUG= 709893 
BUG= 711095 
TEST=ChromeArcUtilTest
TEST=Manually checked MediaView in Files app is working on the first run.

Review-Url: https://codereview.chromium.org/2808353008
Cr-Commit-Position: refs/heads/master@{#464699}

[modify] https://crrev.com/6ea2f510147f3bca05aea7024752e95dcf559912/chrome/browser/chromeos/arc/arc_session_manager.cc
[modify] https://crrev.com/6ea2f510147f3bca05aea7024752e95dcf559912/chrome/browser/chromeos/arc/arc_util.cc
[modify] https://crrev.com/6ea2f510147f3bca05aea7024752e95dcf559912/chrome/browser/chromeos/arc/arc_util.h
[modify] https://crrev.com/6ea2f510147f3bca05aea7024752e95dcf559912/chrome/browser/chromeos/arc/arc_util_unittest.cc
[modify] https://crrev.com/6ea2f510147f3bca05aea7024752e95dcf559912/chrome/browser/chromeos/login/session/user_session_manager.cc
[modify] https://crrev.com/6ea2f510147f3bca05aea7024752e95dcf559912/chrome/browser/chromeos/login/session/user_session_manager.h

Current status:

Waiting for the lgtm on the icon-resource addition CL: https://codereview.chromium.org/2820433002/.
Once that lands, the real notification launching CL will be added and then done.

"The" CL for notification is prepared: https://codereview.chromium.org/2828213002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/534138b6fa2d1f08dda69114567ec27cde498cd0

commit 534138b6fa2d1f08dda69114567ec27cde498cd0
Author: Kazuhiro Inaba <kinaba@chromium.org>
Date: Mon Apr 24 00:46:54 2017

arc: kArcCompatibleFilesystemChosen pref to local state and integer.

For  bug 709893 ,
It needs to be established before profile's KeyedService starts working,
hence is moved to the local state which can be initialized earlier.

For  bug 711095 ,
to implement a one-time UI to show the success of navigation to the user,
this value needs to be tri-state (notyet, done, done-and-notified).
Taking this opportunity to move to local state, this CL changes the type
of the pref from boolean to integer as well.

BUG= 709893 
BUG= 711095 
TEST=ChromeArcUtilTest
TEST=Manually checked MediaView in Files app is working on the first run.

Review-Url: https://codereview.chromium.org/2808353008
Cr-Commit-Position: refs/heads/master@{#464699}
(cherry picked from commit 6ea2f510147f3bca05aea7024752e95dcf559912)

Review-Url: https://codereview.chromium.org/2834323002 .
Cr-Commit-Position: refs/branch-heads/3071@{#150}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}

[modify] https://crrev.com/534138b6fa2d1f08dda69114567ec27cde498cd0/chrome/browser/chromeos/arc/arc_session_manager.cc
[modify] https://crrev.com/534138b6fa2d1f08dda69114567ec27cde498cd0/chrome/browser/chromeos/arc/arc_util.cc
[modify] https://crrev.com/534138b6fa2d1f08dda69114567ec27cde498cd0/chrome/browser/chromeos/arc/arc_util.h
[modify] https://crrev.com/534138b6fa2d1f08dda69114567ec27cde498cd0/chrome/browser/chromeos/arc/arc_util_unittest.cc
[modify] https://crrev.com/534138b6fa2d1f08dda69114567ec27cde498cd0/chrome/browser/chromeos/login/session/user_session_manager.cc
[modify] https://crrev.com/534138b6fa2d1f08dda69114567ec27cde498cd0/chrome/browser/chromeos/login/session/user_session_manager.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c6d7406702779c75f188e7380dd71f211ed4e765

commit c6d7406702779c75f188e7380dd71f211ed4e765
Author: kinaba <kinaba@chromium.org>
Date: Mon Apr 24 06:37:43 2017

arc: Show migration success notification on the next sign-in after migration.

Referring the tri-state preference, shows the notification when needed.
The special case is when the profile was newly created on the device.
In that case, the profile is on the compatible filesystem from the beginning,
we skip showing the migration and mark the pref as if it has been shown.

BUG= 711095 
TEST=Manually tried new/migrated/skipped-migration/guest/supervised accounts.

Review-Url: https://codereview.chromium.org/2828213002
Cr-Commit-Position: refs/heads/master@{#466592}

[modify] https://crrev.com/c6d7406702779c75f188e7380dd71f211ed4e765/chrome/browser/chromeos/arc/arc_migration_guide_notification.cc
[modify] https://crrev.com/c6d7406702779c75f188e7380dd71f211ed4e765/chrome/browser/chromeos/arc/arc_migration_guide_notification.h
[modify] https://crrev.com/c6d7406702779c75f188e7380dd71f211ed4e765/chrome/browser/chromeos/login/session/user_session_manager.cc

#2/#6 is merged for fixing other bugs.

#8 is the CL for this specific bug which I'm now requesting merge approval.

Thanks for the approval.

I think I wrongly read goldeneye... canary build with the change was not generated yet.
I'll merge asap once it is baked onto the canary.

Your change meets the bar and is auto-approved for M59. Please go ahead and merge the CL to branch 3071 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), gkihumba@(ChromeOS), Abdul Syed@(Desktop)

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

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9ad42d0a1f85ca03d84eb5ae8f9d8743c32f2c05

commit 9ad42d0a1f85ca03d84eb5ae8f9d8743c32f2c05
Author: Kazuhiro Inaba <kinaba@chromium.org>
Date: Wed Apr 26 11:49:50 2017

arc: Show migration success notification on the next sign-in after migration.

Referring the tri-state preference, shows the notification when needed.
The special case is when the profile was newly created on the device.
In that case, the profile is on the compatible filesystem from the beginning,
we skip showing the migration and mark the pref as if it has been shown.

BUG= 711095 
TEST=Manually tried new/migrated/skipped-migration/guest/supervised accounts.

Review-Url: https://codereview.chromium.org/2828213002
Cr-Commit-Position: refs/heads/master@{#466592}
(cherry picked from commit c6d7406702779c75f188e7380dd71f211ed4e765)

Review-Url: https://codereview.chromium.org/2840203002 .
Cr-Commit-Position: refs/branch-heads/3071@{#223}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}

[modify] https://crrev.com/9ad42d0a1f85ca03d84eb5ae8f9d8743c32f2c05/chrome/browser/chromeos/arc/arc_migration_guide_notification.cc
[modify] https://crrev.com/9ad42d0a1f85ca03d84eb5ae8f9d8743c32f2c05/chrome/browser/chromeos/arc/arc_migration_guide_notification.h
[modify] https://crrev.com/9ad42d0a1f85ca03d84eb5ae8f9d8743c32f2c05/chrome/browser/chromeos/login/session/user_session_manager.cc

M59 now has the notification at the first sign-in after a successful migration.

Verified on ChromeOS 9532.0.0, 60.0.3092.0

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6f832b7a5ad0f23098edfc38d4a2c60c2b66b3ff

commit 6f832b7a5ad0f23098edfc38d4a2c60c2b66b3ff
Author: kinaba <kinaba@chromium.org>
Date: Mon May 22 05:57:56 2017

Delete a TODO comment that had already been addressed.

I should have updated this TODO in https://codereview.chromium.org/2828213002.

BUG= 711095 
TEST=None (only a comment change)

Review-Url: https://codereview.chromium.org/2895113002
Cr-Commit-Position: refs/heads/master@{#473511}

[modify] https://crrev.com/6f832b7a5ad0f23098edfc38d4a2c60c2b66b3ff/chrome/browser/chromeos/arc/arc_util.h