Thanks for the bug.

We want to skip UserSessionManager::UpdateEasyUnlockKeys when using PIN to sign-in. These keys are wrapping user password and we don't want to re-create them wrapping the PIN.

Should be able to just check |user_context.IsUsingPin()| in https://cs.chromium.org/chromium/src/chrome/browser/chromeos/login/session/user_session_manager.cc?l=1802&rcl=f8fbfbbbf0b7aa42606eb18dc3672a96d95f8990

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f26b3a8d7e32ee9b257dd5819344aa4e3ee3534c

commit f26b3a8d7e32ee9b257dd5819344aa4e3ee3534c
Author: Wenzhao Zang <wzang@chromium.org>
Date: Wed Oct 03 18:35:47 2018

cros: Skip UserSessionManager::UpdateEasyUnlockKeys when using PIN

Bug:  850250 
Change-Id: I1a7af66367665bcb1577b5c6efc3f2e5d2748113
Reviewed-on: https://chromium-review.googlesource.com/1171801
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596295}
[modify] https://crrev.com/f26b3a8d7e32ee9b257dd5819344aa4e3ee3534c/chrome/browser/chromeos/login/session/user_session_manager.cc