Add Alternative Service field trial.

Before this CL:
 * If "use_alternative_service" QUIC trial param was set, both same host and
   different host Alt-Svc headers were parsed and used.  If this param was not
   set, no Alt-Svc headers were parsed, and in-memory entries (from
   Alternate-protocol headers or loaded from disk) were only used if they
   referred to the same host.

After this CL:
 * AltSvc field trial controls whether Alt-Svc headers are parsed.
 * "enable_alternative_service_with_different_host" QUIC trial param control
   whether in-memory Alt-Svc entries with different host (parsed in current
   session or loaded from disk) are used.

Default values are not changed by this CL.

This CL allows testing of same-host Alt-Svc header behavior.  If no issues are
encountered, parsing Alt-Svc headers and using same-host entries can be enabled
by default, and Alternate-Protocols removed.

BUG=581331

Review URL: https://codereview.chromium.org/1639913002

Cr-Commit-Position: refs/heads/master@{#372348}

1 files changed, 2 insertions, 1 deletions

diff --git a/chromecast/browser/url_request_context_factory.cc b/chromecast/browser/url_request_context_factory.cc
index 41f4b5b..bcfad11 100644
--- a/chromecast/browser/url_request_context_factory.cc
+++ b/chromecast/browser/url_request_context_factory.cc
@@ -296,7 +296,8 @@ void URLRequestContextFactory::PopulateNetworkSessionParams(
   // TODO(lcwu): http://crbug.com/329681. Remove this once spdy is enabled
   // by default at the content level.
   params->next_protos = net::NextProtosSpdy31();
-  params->use_alternative_services = true;
+  params->parse_alternative_services = true;
+  params->enable_alternative_service_with_different_host = true;
 }
 
 net::URLRequestContext* URLRequestContextFactory::CreateSystemRequestContext() {