Disable a SyncTest correctly.

This reverts https://codereview.chromium.org/34603003 and disables the test correctly.

I have followed the example of https://codereview.chromium.org/42103005.

You can see that the buildbot was trying to run the test today:
http://build.chromium.org/p/chromium.linux/builders/Android%20Tests/builds/9870/steps/chromiumtestshell_instrumentation_tests/logs/stdio

BUG=322562,309997

Review URL: https://codereview.chromium.org/83173006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236824 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236824