On further thought, we should instead try to submit keyboard events so that the autotest is completely independent of UI and does not rely on autotestPrivate.

I spoke with Sarah about it today. It 'should' be fairly trivial to do.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7df02c0de4bab86ea229a6a09bb8cc65b1782593

commit 7df02c0de4bab86ea229a6a09bb8cc65b1782593
Author: Sarah Hu <xiaoyinh@chromium.org>
Date: Sat Dec 02 00:14:31 2017

Modify Autotest API to support views based lockscreen

Bug:  781998 
Change-Id: I11a456b1341d044b1370652c337f105e0bef649a
Reviewed-on: https://chromium-review.googlesource.com/803622
Commit-Queue: Xiaoyin Hu <xiaoyinh@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521137}
[modify] https://crrev.com/7df02c0de4bab86ea229a6a09bb8cc65b1782593/chrome/browser/chromeos/login/lock/screen_locker.h
[modify] https://crrev.com/7df02c0de4bab86ea229a6a09bb8cc65b1782593/chrome/browser/extensions/api/autotest_private/autotest_private_api.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8f0082cfcf0bf54ccf285350a584523e38e7f69a

commit 8f0082cfcf0bf54ccf285350a584523e38e7f69a
Author: Xiaoyin Hu <xiaoyinh@chromium.org>
Date: Wed Dec 06 22:27:48 2017

Revert "Modify Autotest API to support views based lockscreen"

This reverts commit 7df02c0de4bab86ea229a6a09bb8cc65b1782593.

Reason for revert: Failed desktopui_ScreenLocker autotest

Original change's description:
> Modify Autotest API to support views based lockscreen
> 
> Bug:  781998 
> Change-Id: I11a456b1341d044b1370652c337f105e0bef649a
> Reviewed-on: https://chromium-review.googlesource.com/803622
> Commit-Queue: Xiaoyin Hu <xiaoyinh@chromium.org>
> Reviewed-by: Jacob Dufault <jdufault@chromium.org>
> Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#521137}

TBR=achuith@chromium.org,jdufault@chromium.org,xiaoyinh@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug:  781998 
Change-Id: I547a15a15d2cf3b95986e8cfbf548b95cd0b3087
Reviewed-on: https://chromium-review.googlesource.com/812264
Reviewed-by: Xiaoyin Hu <xiaoyinh@chromium.org>
Commit-Queue: Xiaoyin Hu <xiaoyinh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522225}
[modify] https://crrev.com/8f0082cfcf0bf54ccf285350a584523e38e7f69a/chrome/browser/chromeos/login/lock/screen_locker.h
[modify] https://crrev.com/8f0082cfcf0bf54ccf285350a584523e38e7f69a/chrome/browser/extensions/api/autotest_private/autotest_private_api.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4

commit 0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4
Author: Sarah Hu <xiaoyinh@chromium.org>
Date: Tue Dec 12 18:00:05 2017

Modify Autotest API to support views based lockscreen

1. re-landing the change of
https://chromium-review.googlesource.com/c/chromium/src/+/812264
2. Add a mojo call IsAuthenticating to check the authentication state
in ash lock screen.

Bug:  781998 
Change-Id: I40a985cced8fe9cdaad404b068ffeacc669677a4
Reviewed-on: https://chromium-review.googlesource.com/816022
Commit-Queue: Xiaoyin Hu <xiaoyinh@chromium.org>
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523474}
[modify] https://crrev.com/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4/ash/login/login_screen_controller.cc
[modify] https://crrev.com/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4/ash/login/login_screen_controller.h
[modify] https://crrev.com/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4/ash/public/interfaces/login_screen.mojom
[modify] https://crrev.com/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4/chrome/browser/chromeos/login/lock/screen_locker.h
[modify] https://crrev.com/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4/chrome/browser/extensions/api/autotest_private/autotest_private_api.cc
[modify] https://crrev.com/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4/chrome/browser/extensions/api/autotest_private/autotest_private_api.h
[modify] https://crrev.com/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4/chrome/browser/ui/ash/login_screen_client.cc
[modify] https://crrev.com/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4/chrome/browser/ui/ash/login_screen_client.h
[modify] https://crrev.com/0bfd187cc3d14d705ca5c79d0c89dbcd3dfb83b4/chrome/common/extensions/api/autotest_private.idl

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/38fbbae44d3c73a18602413c52bb8b40532c87b4

commit 38fbbae44d3c73a18602413c52bb8b40532c87b4
Author: Sarah Hu <xiaoyinh@chromium.org>
Date: Tue Dec 12 21:51:02 2017

Modify autotest to support views based lockscreen.

BUG= chromium:781998 
TEST=test_that --board=$BOARD <ip> desktopui_ScreenLocker

Change-Id: I4e2f750b5e6c75f77ccfacaae498e02b716f982d
Reviewed-on: https://chromium-review.googlesource.com/767127
Commit-Ready: Xiaoyin Hu <xiaoyinh@chromium.org>
Tested-by: Xiaoyin Hu <xiaoyinh@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>

[modify] https://crrev.com/38fbbae44d3c73a18602413c52bb8b40532c87b4/client/site_tests/desktopui_ScreenLocker/desktopui_ScreenLocker.py
[add] https://crrev.com/38fbbae44d3c73a18602413c52bb8b40532c87b4/client/cros/input_playback/keyboard_b+a+d+enter

 Issue 792565  has been merged into this issue.