Fix GetActiveProxyConfigDictionary crash

Fix ProxyConfigServiceImpl::GetActiveProxyConfigDictionary when
called in an envinronment without a primary user (e.g. public
sessions only setup).

Bug: 910218
Change-Id: Ibe5b6dc50cb4260c325c530ebce5e15e6af3eaa6
Reviewed-on: https://chromium-review.googlesource.com/c/1424888
Commit-Queue: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624937}
1 file changed