Change |use_alternative_service| not to disable Alternate Protocols.

Currently, HttpNetworkSession::Params::use_alternative_service controls both
Alternate Protocols and Alternative Services.  However, Alternate Protocols is
fully rolled out, therefore there is not need to disable it.

This CL changes |use_alternative_service| to
 * disable parsing Alt-Svc headers (but not Alternate-Protocol ones);
 * disable following saved alternative service entries that point to different
   hosts (but not ones that point to the same host).
The latter is necessary because a browser session might have this flag enabled
and might save alternative services to disk, which we do not really want to
follow in the next browser session if the flag is disabled.  (Ones discovered
through Alt-Svc pointing to the same host will still be respected.)

BUG=524141

Review URL: https://codereview.chromium.org/1310583002

Cr-Commit-Position: refs/heads/master@{#345640}

0 files changed, 0 insertions, 0 deletions