GitLab

* Add host parameter to QuicTestPacketMaker constructor to allow for non-default
  hostnames in generated packets.
* Change hostname in QuicNetworkTransactionTest.SecureResourceOver* in
  anticipation for a future CL that will enforce certificate validation in these
  unittests.
* s/kServerHostname/kDefaultServerHostName/ in QuicHttpStreamTest to match
  QuicStreamFactoryTest.

BUG=474217

Review URL: https://codereview.chromium.org/1142523004

Cr-Commit-Position: refs/heads/master@{#329890}