cros: Fix crash likely caused by ExistingUserController::DeviceSettingsChanged.

This function initializes the login screen multiple times, which views login did
not support.

Bug: 859559
Change-Id: I57f3282b12c604074f9d34760f9804c18eee2d09
Reviewed-on: https://chromium-review.googlesource.com/1125129
Reviewed-by: Xiaoyin Hu <xiaoyinh@chromium.org>
Commit-Queue: Jacob Dufault <jdufault@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575705}
2 files changed