Adapt user check to multi user architecture.

BUG:https://crosswalk-project.org/jira/browse/XWALK-1649

Change-Id: I2e38c4582e7b0bf1a024ffdad22d1bd14056bb11
Signed-off-by: Baptiste DURAND <baptiste.durand@open.eurogiciel.org>
Merge pull request #1912 from eurogiciel-oss/XWALK-1649

Adapt user check to multi user architecture.