[net/dns] Serve requests from HOSTS file if possible.
If the DnsConfig is available, we can serve the requests synchronously in Resolve. However, we might not receive the DnsConfig until the Job is placed in the queue. In that case, we attempt to serve the jobs once DnsConfig is available.
BUG=
114826
TEST=./net_unittests --gtest_filter=HostResolverImplTest.ServeFromHosts
Committed:
http://src.chromium.org/viewvc/chrome?view=rev&revision=126559