[SyncFS] Deflake SyncFileSystemServiceTest.SimpleLocalSyncFlow

[SyncFS] Deflake SyncFileSystemServiceTest.SimpleLocalSyncFlow

Fix mock expectation for the flaky test.

BUG=408443
TEST=unit_tests --gtest_filter=SyncFileSystemServiceTest.SimpleLocalSyncFlow

Committed: https://crrev.com/af2ddaa039f67b19e193a8836aeec43bd45fd839
Cr-Commit-Position: refs/heads/master@{#292850}

[tzik, 2014-09-01 07:17:45]

tzik@chromium.org changed reviewers:
+ peria@chromium.org

[tzik, 2014-09-01 07:17:46]

PTL

[peria, 2014-09-01 07:22:53]

lgtm

[tzik, 2014-09-01 07:44:04]

The CQ bit was checked by tzik@chromium.org

[commit-bot: I haz the power, 2014-09-01 07:45:00]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tzik@chromium.org/524193004/1

[commit-bot: I haz the power, 2014-09-01 08:37:13]

Committed patchset #1 (id:1) as 40a9371fcc6ef366b25e643b96b1f3eba057629f

[commit-bot: I haz the power, 2014-09-10 03:16:05]

Patchset 1 (id:??) landed as
https://crrev.com/af2ddaa039f67b19e193a8836aeec43bd45fd839
Cr-Commit-Position: refs/heads/master@{#292850}