Fix failing sync integration tests.

      TwoClientLivePreferencesSyncTest.Security was failing due to a couple of
EXPECT_NEs that ought to have been EXPECT_EQs.

TwoClientLiveAutofillSyncTest.Client1HasData was failing due to a change
in autofill behavior introduced in r55781 to fix security bug crbug.com/51727.

This changelist also includes a clarification in the logic used by
TwoClientLiveAutofillSyncTest.BothHaveData.

BUG=51727,51956
TEST=sync_integration_tests

Review URL: http://codereview.chromium.org/3169019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@56469 0039d316-1c4b-4281-b951-d872f2087c98