Network validation prevents networks claiming to provide internet connectivity
from becoming the default network in cases where internet connectivity is not
found to actually exist.
If a captive portal is encountered the appropriate broadcasts and notifications
are surfaced to allow apps to handle signing in. If no app handles signing in,
my system app will handle it.
Bug:15409233
Bug:15409354
Change-Id: Ie240d7eac4bdbab8cc7578782bd72d8b26de7951
869868be65