vpn-manager: Update to build against libchrome-271506

BUG=chromium:375032
TEST=`USE='vpn' FEATURES=test emerge-$BOARD platform2`

Change-Id: I323b76017c66bab1bc0403ddf9003a6aa18955d6
Reviewed-on: https://chromium-review.googlesource.com/201051
Tested-by: Ben Chan <benchan@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
5 files changed