Revert of Remove support for Alt-Svc/Alternate Protocol Probability

ios/crnet/crnet_environment.mm

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ios/crnet/crnet_environment.h"
 
 #import <Foundation/Foundation.h>
 
 #include <utility>
 
@@ skipping 424 matching lines @@
   params.proxy_service = main_context_->proxy_service();
   params.ssl_config_service = main_context_->ssl_config_service();
   params.http_auth_handler_factory = main_context_->http_auth_handler_factory();
   params.network_delegate = main_context_->network_delegate();
   params.http_server_properties = main_context_->http_server_properties();
   params.net_log = main_context_->net_log();
   params.enable_spdy31 = spdy_enabled();
   params.enable_http2 = spdy_enabled();
   params.parse_alternative_services = false;
   params.enable_quic = quic_enabled();
+  params.alternative_service_probability_threshold =
+      alternate_protocol_threshold_;
 
   if (!params.channel_id_service) {
     // The main context may not have a ChannelIDService, since it is lazily
     // constructed. If not, build an ephemeral ChannelIDService with no backing
     // disk store.
     // TODO(ellyjones): support persisting ChannelID.
     params.channel_id_service = new net::ChannelIDService(
         new net::DefaultChannelIDStore(NULL),
         base::WorkerPool::GetTaskRunner(true));
   }
@@ skipping 34 matching lines @@
 
   return user_agent_settings->GetUserAgent();
 }
 
 void CrNetEnvironment::ClearCache(ClearCacheCallback callback) {
   PostToNetworkThread(
       FROM_HERE,
       base::Bind(&net::ClearHttpCache, main_context_getter_,
                  network_io_thread_->task_runner(), base::BindBlock(callback)));
 }