Also powerwash! :)

I confirmed that ShowEncryptionMigrationScreen also fall-back to the webui-based oobe.

If this is blocking https://bugs.chromium.org/p/chromium/issues/detail?id=838876 we need to get this fixed soon as that bug is blocking beta promotion we are hoping to do next week.

There seem to be a number of bugs around the log in screen crashing and acting badly on 68, we need to get these worked out soon.

It's working in process.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a532eef9eefce1f1791bc00825b74ad0c303a29a

commit a532eef9eefce1f1791bc00825b74ad0c303a29a
Author: Sarah Hu <xiaoyinh@chromium.org>
Date: Thu Jun 07 00:39:26 2018

wire up some special screens to views login screen

1. ShowPasswordChangedDialog
2. ShowWhitelistCheckFailedError
3. ShowUnrecoverableCryptohomeErrorDialog

Bug:  828058 
Change-Id: I7269d927e9239319b4a24e4655d0ceaadf5c044b
Reviewed-on: https://chromium-review.googlesource.com/1087772
Commit-Queue: Xiaoyin Hu <xiaoyinh@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565124}
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/BUILD.gn
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/app_launch_signin_screen.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/app_launch_signin_screen.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/existing_user_controller.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/existing_user_controller.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/lock/webui_screen_locker.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/lock/webui_screen_locker.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/fake_login_display_host.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/fake_login_display_host.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_display.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_display_host.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_display_host_common.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_display_host_common.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_display_host_mojo.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_display_host_mojo.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_display_mojo.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_display_webui.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_display_webui.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/login_feedback.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/mock_login_display_host.h
[rename] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/oobe_ui_dialog_delegate.cc
[rename] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/chromeos/login/ui/oobe_ui_dialog_delegate.h
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
[modify] https://crrev.com/a532eef9eefce1f1791bc00825b74ad0c303a29a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/df5e0b81e3af246cbc9635d9d1d8f9989ba713a0

commit df5e0b81e3af246cbc9635d9d1d8f9989ba713a0
Author: Sarah Hu <xiaoyinh@chromium.org>
Date: Wed Jun 13 22:04:19 2018

Add some special screens in views login screen part 2

Add the following screens:
1. ShowErrorScreen
2. ShowSigninUI

Bug:  828058 
Change-Id: Id632fd49b4e1575ad5443b5f315067bdbe08efd9
Reviewed-on: https://chromium-review.googlesource.com/1098457
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Commit-Queue: Xiaoyin Hu <xiaoyinh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567011}
[modify] https://crrev.com/df5e0b81e3af246cbc9635d9d1d8f9989ba713a0/chrome/browser/chromeos/login/ui/login_display_host_mojo.cc
[modify] https://crrev.com/df5e0b81e3af246cbc9635d9d1d8f9989ba713a0/chrome/browser/chromeos/login/ui/login_display_host_mojo.h
[modify] https://crrev.com/df5e0b81e3af246cbc9635d9d1d8f9989ba713a0/chrome/browser/chromeos/login/ui/login_display_mojo.cc