The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/334a73b3008aa84623f819beda6af78d56b30e35

commit 334a73b3008aa84623f819beda6af78d56b30e35
Author: Mikel Astiz <mastiz@chromium.org>
Date: Fri Oct 19 13:02:16 2018

Add more PASSWORDS integration tests

They verify some otherwise-untested but privacy-sensitive requirements
of what is being sent on the wire, where most (without custom
passphrase) or all (with custom passphrase) proto fields should be
encrypted.

The actual verification is done using the state in the fake server,
which is assumed to store committed content without pruning. This holds
true today and is unlikely to change in the future.

Bug:  856941 , 870624 
Change-Id: I9198ca69c53d55a80f4b2a0c55cd5265e57741aa
Reviewed-on: https://chromium-review.googlesource.com/c/1290809
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Reviewed-by: Mohamed Amir Yosef <mamir@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601126}
[modify] https://crrev.com/334a73b3008aa84623f819beda6af78d56b30e35/chrome/browser/sync/test/integration/single_client_passwords_sync_test.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d370f99315e7b7fb9cfd3e3eb51480d0c4788774

commit d370f99315e7b7fb9cfd3e3eb51480d0c4788774
Author: Mikel Astiz <mastiz@chromium.org>
Date: Fri Oct 19 19:39:21 2018

Add PASSWORDS sync support to USS codepath

ModelTypeWorker et al need to be updated to support PASSWORDS, which is
the only datatype with a custom encryption mechanism (always encrypted).
This involves implementing logic analogous to the directory counterpart,
which uses passwords-specific proto fields and other requirements like
clearing out certain fields if custom passphrase is set.

The introduced code changes are not exercised in production yet because
there's no USS (or pseudo-USS) implementation for PASSWORDS.

Bug:  856941 , 870624 
Change-Id: Iae7c9a9a76f87dbd2406ed8e56589dc629f07c6a
Reviewed-on: https://chromium-review.googlesource.com/c/1288537
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Reviewed-by: Mohamed Amir Yosef <mamir@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601257}
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine/sync_encryption_handler.h
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/model_type_registry.cc
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/model_type_registry.h
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/model_type_worker.cc
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/model_type_worker.h
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/model_type_worker_unittest.cc
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/non_blocking_type_commit_contribution.cc
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/non_blocking_type_commit_contribution.h
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/non_blocking_type_commit_contribution_unittest.cc
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/sync_encryption_handler_impl.cc
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/uss_migrator.cc
[modify] https://crrev.com/d370f99315e7b7fb9cfd3e3eb51480d0c4788774/components/sync/engine_impl/uss_migrator_unittest.cc