[Sync::USS] Introducing PasswordModelTypeController

Bug: 902349
Change-Id: Ic8f20ba353bf9805d79916f440fe10137a97aff7
Reviewed-on: https://chromium-review.googlesource.com/c/1325981
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608009}
7 files changed