[Sync::USS] Decrypt passwords in the ModelTypeWorker for full-blown USS

Bug: 902349
Change-Id: Ibd685911d52ae19c62b06caf47688abad081d243
Reviewed-on: https://chromium-review.googlesource.com/c/1333760
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611233}
4 files changed