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

ios/chrome/browser/ios_chrome_io_thread.mm

 // Copyright 2015 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/chrome/browser/ios_chrome_io_thread.h"
 
 #include <stddef.h>
 
 #include <utility>
 #include <vector>
@@ skipping 616 matching lines @@
   params->testing_fixed_https_port = globals.testing_fixed_https_port;
   globals.enable_tcp_fast_open_for_ssl.CopyToIfSet(
       &params->enable_tcp_fast_open_for_ssl);
 
   globals.enable_spdy31.CopyToIfSet(&params->enable_spdy31);
   globals.enable_http2.CopyToIfSet(&params->enable_http2);
   globals.parse_alternative_services.CopyToIfSet(
       &params->parse_alternative_services);
   globals.enable_alternative_service_with_different_host.CopyToIfSet(
       &params->enable_alternative_service_with_different_host);
+  globals.alternative_service_probability_threshold.CopyToIfSet(
+      &params->alternative_service_probability_threshold);
 
   globals.enable_npn.CopyToIfSet(&params->enable_npn);
 
   globals.enable_quic.CopyToIfSet(&params->enable_quic);
   globals.enable_quic_for_proxies.CopyToIfSet(&params->enable_quic_for_proxies);
   globals.quic_always_require_handshake_confirmation.CopyToIfSet(
       &params->quic_always_require_handshake_confirmation);
   globals.quic_disable_connection_pooling.CopyToIfSet(
       &params->quic_disable_connection_pooling);
   globals.quic_load_server_info_timeout_srtt_multiplier.CopyToIfSet(
@@ skipping 150 matching lines @@
   quic_user_agent_id.push_back(' ');
   quic_user_agent_id.append(web::BuildOSCpuInfo());
   globals->quic_user_agent_id.set(quic_user_agent_id);
 
   net::QuicVersion version = GetQuicVersion(quic_trial_params);
   if (version != net::QUIC_VERSION_UNSUPPORTED) {
     net::QuicVersionVector supported_versions;
     supported_versions.push_back(version);
     globals->quic_supported_versions.set(supported_versions);
   }
+
+  double threshold =
+      GetAlternativeProtocolProbabilityThreshold(quic_trial_params);
+  if (threshold >= 0 && threshold <= 1) {
+    globals->alternative_service_probability_threshold.set(threshold);
+    globals->http_server_properties->SetAlternativeServiceProbabilityThreshold(
+        threshold);
+  }
 }
 
 bool IOSChromeIOThread::ShouldEnableQuic(base::StringPiece quic_trial_group) {
   return quic_trial_group.starts_with(kQuicFieldTrialEnabledGroupName) ||
          quic_trial_group.starts_with(kQuicFieldTrialHttpsEnabledGroupName);
 }
 
 bool IOSChromeIOThread::ShouldEnableQuicForProxies(
     base::StringPiece quic_trial_group) {
   return ShouldEnableQuic(quic_trial_group) ||
          ShouldEnableQuicForDataReductionProxy();
 }
 
 bool IOSChromeIOThread::ShouldEnableQuicForDataReductionProxy() {
   return data_reduction_proxy::params::IsIncludedInQuicFieldTrial();
 }
 
 net::QuicTagVector IOSChromeIOThread::GetQuicConnectionOptions(
     const VariationParameters& quic_trial_params) {
   VariationParameters::const_iterator it =
       quic_trial_params.find("connection_options");
   if (it == quic_trial_params.end()) {
     return net::QuicTagVector();
   }
 
   return net::QuicUtils::ParseQuicConnectionOptions(it->second);
 }
 
+double IOSChromeIOThread::GetAlternativeProtocolProbabilityThreshold(
+    const VariationParameters& quic_trial_params) {
+  double value;
+  // TODO(bnc): Remove when new parameter name rolls out and server
+  // configuration is changed.
+  if (base::StringToDouble(
+          GetVariationParam(quic_trial_params,
+                            "alternate_protocol_probability_threshold"),
+          &value)) {
+    return value;
+  }
+  if (base::StringToDouble(
+          GetVariationParam(quic_trial_params,
+                            "alternative_service_probability_threshold"),
+          &value)) {
+    return value;
+  }
+  return -1;
+}
+
 bool IOSChromeIOThread::ShouldQuicAlwaysRequireHandshakeConfirmation(
     const VariationParameters& quic_trial_params) {
   return base::LowerCaseEqualsASCII(
       GetVariationParam(quic_trial_params,
                         "always_require_handshake_confirmation"),
       "true");
 }
 
 bool IOSChromeIOThread::ShouldQuicDisableConnectionPooling(
     const VariationParameters& quic_trial_params) {
@@ skipping 169 matching lines @@
 
   globals->system_http_network_session.reset(
       new net::HttpNetworkSession(system_params));
   globals->system_http_transaction_factory.reset(
       new net::HttpNetworkLayer(globals->system_http_network_session.get()));
   context->set_http_transaction_factory(
       globals->system_http_transaction_factory.get());
 
   return context;
 }