Last time I heard fukino's not working on this change.

fukino@ is back today and is going to take this over.  Some points from our offline sync:
 - Its possible that the failure screen could be shown briefly during shutdown, so may want to take the stats after a delay
 - Profile removal actually happens before the error screen is shown, so measuring how many users click through is not as useful, though would still be good to know
 - Should probably count how many times the profile removal was called, how many times it returned success/failure.  This will help account for shutdown scenarios where cryptohome may already be stopped.
 - We may have a race condition on shutdown.  Filed https://bugs.chromium.org/p/chromium/issues/detail?id=727980 to investigate.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4e58ceae8e2e76c9f95b835827b588b4da3810f4

commit 4e58ceae8e2e76c9f95b835827b588b4da3810f4
Author: fukino <fukino@chromium.org>
Date: Fri Jun 02 06:17:42 2017

cros: Add UMA metrics in migration UI to get more information from migration failures.

To get more information about migration failures from UMA stats, I'd like to add/update following histograms.

1) Cryptohome.MigrationUI.MigrationResult (new)
We'd like to know the migration result, including errors which only Chrome knows (i.e. Chrome failed to mount existing vault)

2) Cryptohome.MigrationUI.RemoveCryptohomeResult (new)
Chrome UI code tries to remove the user's cryptohome when migration fails.
We'd like to know if the removal succeeds, which we don't have information before.

3) Cryptohome.MigrationUI.VisibleScreen (new)
In theory, a screen can be displayed as a flash (especially in shutdown sequence). We'd like to know how many times each screen *actually* gets visible to users. (i.e. displayed at least 1 second.)

4) Cryptohome.MigrationUI.UserChoice (expansion on existing one)
We have recorded click events on "Update" and "Skip" button on the migration UI. We'd like to know about other buttons such as "Restart" on error screen, too.

BUG= 726213 
TEST=checked chrome://histograms by disabling auto restart after migration.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2910423002
Cr-Commit-Position: refs/heads/master@{#476592}

[modify] https://crrev.com/4e58ceae8e2e76c9f95b835827b588b4da3810f4/chrome/browser/resources/chromeos/login/encryption_migration.html
[modify] https://crrev.com/4e58ceae8e2e76c9f95b835827b588b4da3810f4/chrome/browser/resources/chromeos/login/encryption_migration.js
[modify] https://crrev.com/4e58ceae8e2e76c9f95b835827b588b4da3810f4/chrome/browser/resources/chromeos/login/screen_encryption_migration.js
[modify] https://crrev.com/4e58ceae8e2e76c9f95b835827b588b4da3810f4/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
[modify] https://crrev.com/4e58ceae8e2e76c9f95b835827b588b4da3810f4/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.h
[modify] https://crrev.com/4e58ceae8e2e76c9f95b835827b588b4da3810f4/tools/metrics/histograms/enums.xml
[modify] https://crrev.com/4e58ceae8e2e76c9f95b835827b588b4da3810f4/tools/metrics/histograms/histograms.xml

Requesting a merge to get more information from Dev/Beta

Your change meets the bar and is auto-approved for M60. Please go ahead and merge the CL to branch 3112 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), josafat@(ChromeOS), bustamante@(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/+/eca63e9f4523341a3d46b4e0c515d8b3c17c092e

commit eca63e9f4523341a3d46b4e0c515d8b3c17c092e
Author: Naoki Fukino <fukino@chromium.org>
Date: Mon Jun 05 03:26:51 2017

cros: Add UMA metrics in migration UI to get more information from migration failures.

To get more information about migration failures from UMA stats, I'd like to add/update following histograms.

1) Cryptohome.MigrationUI.MigrationResult (new)
We'd like to know the migration result, including errors which only Chrome knows (i.e. Chrome failed to mount existing vault)

2) Cryptohome.MigrationUI.RemoveCryptohomeResult (new)
Chrome UI code tries to remove the user's cryptohome when migration fails.
We'd like to know if the removal succeeds, which we don't have information before.

3) Cryptohome.MigrationUI.VisibleScreen (new)
In theory, a screen can be displayed as a flash (especially in shutdown sequence). We'd like to know how many times each screen *actually* gets visible to users. (i.e. displayed at least 1 second.)

4) Cryptohome.MigrationUI.UserChoice (expansion on existing one)
We have recorded click events on "Update" and "Skip" button on the migration UI. We'd like to know about other buttons such as "Restart" on error screen, too.

BUG= 726213 
TEST=checked chrome://histograms by disabling auto restart after migration.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2910423002
Cr-Original-Commit-Position: refs/heads/master@{#476592}
Review-Url: https://codereview.chromium.org/2917303002 .
Cr-Commit-Position: refs/branch-heads/3112@{#139}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}

[modify] https://crrev.com/eca63e9f4523341a3d46b4e0c515d8b3c17c092e/chrome/browser/resources/chromeos/login/encryption_migration.html
[modify] https://crrev.com/eca63e9f4523341a3d46b4e0c515d8b3c17c092e/chrome/browser/resources/chromeos/login/encryption_migration.js
[modify] https://crrev.com/eca63e9f4523341a3d46b4e0c515d8b3c17c092e/chrome/browser/resources/chromeos/login/screen_encryption_migration.js
[modify] https://crrev.com/eca63e9f4523341a3d46b4e0c515d8b3c17c092e/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
[modify] https://crrev.com/eca63e9f4523341a3d46b4e0c515d8b3c17c092e/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.h
[modify] https://crrev.com/eca63e9f4523341a3d46b4e0c515d8b3c17c092e/tools/metrics/histograms/enums.xml
[modify] https://crrev.com/eca63e9f4523341a3d46b4e0c515d8b3c17c092e/tools/metrics/histograms/histograms.xml