[Sync] Verify that correct value of CookieJarMismatch is passed to SyncCycleContext

SingleClientSessionsSyncTest.CookieJarMismatch test is flaky. It fails on the
step when signed in account gets included in the list of accounts in cookie jar.
In this case value of cookie_jar_mismatch should turn to false.

I wasn't able to reproduce this bug, nor I was able to find scenario how this
test could fail.

I'm adding a check that ensures correct value of cookie_jar_mismatch is passed
to sync engine. The next time this test fails it will be clear if failure caused
by incorrect value or the value wasn't delivered to the server.

R=pnoland@chromium.org
BUG=789129

Change-Id: I508e5d37083e98b2c02e1bf3a35917dad3a9645f
Reviewed-on: https://chromium-review.googlesource.com/804556
Commit-Queue: Pavel Yatsuk <pavely@chromium.org>
Reviewed-by: Patrick Noland <pnoland@google.com>
Cr-Commit-Position: refs/heads/master@{#521583}
3 files changed