Change the interface of GetAlternativeServicesFor, always return the best Alt-Svc entry.

net/quic/quic_stream_factory.cc

 // Copyright (c) 2012 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 "net/quic/quic_stream_factory.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
 #include "base/location.h"
 #include "base/macros.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/rand_util.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/values.h"
 #include "net/base/net_errors.h"
 #include "net/base/socket_performance_watcher.h"
 #include "net/base/socket_performance_watcher_factory.h"
 #include "net/cert/cert_verifier.h"
 #include "net/cert/ct_verifier.h"
 #include "net/dns/host_resolver.h"
 #include "net/dns/single_request_host_resolver.h"
-#include "net/http/http_server_properties.h"
 #include "net/quic/crypto/channel_id_chromium.h"
 #include "net/quic/crypto/proof_verifier_chromium.h"
 #include "net/quic/crypto/properties_based_quic_server_info.h"
 #include "net/quic/crypto/quic_random.h"
 #include "net/quic/crypto/quic_server_info.h"
 #include "net/quic/port_suggester.h"
 #include "net/quic/quic_chromium_client_session.h"
 #include "net/quic/quic_clock.h"
 #include "net/quic/quic_connection.h"
 #include "net/quic/quic_connection_helper.h"
@@ skipping 662 matching lines @@
   if (!srtt)
     srtt = kDefaultRTT;
   return base::TimeDelta::FromMicroseconds(srtt);
 }
 
 void QuicStreamFactory::set_quic_server_info_factory(
     QuicServerInfoFactory* quic_server_info_factory) {
   quic_server_info_factory_.reset(quic_server_info_factory);
 }
 
+bool QuicStreamFactory::CanUseExistingSession(QuicServerId server_id,
+                                              PrivacyMode privacy_mode,
+                                              StringPiece origin_host) {
+  // TODO(zhongyi): crbug.com/498823 - delete active_sessions_.empty() checks.

[Ryan Hamilton, 2016/01/05 23:51:58]

Can you say more about this?

[Zhongyi Shi, 2016/01/06 02:31:40]

I talked to raman earlier about that bug, this is a temporary fix for the
android crash issue. He said once we finally resolve that issue, we can remove
the empty() checks here. 

+  if (active_sessions_.empty())
+    return false;
+  SessionMap::iterator it = active_sessions_.find(server_id);
+  if (it == active_sessions_.end())
+    return false;
+  QuicChromiumClientSession* session = it->second;
+  return session->CanPool(origin_host.as_string(), privacy_mode);
+}
+
 int QuicStreamFactory::Create(const HostPortPair& host_port_pair,
                               PrivacyMode privacy_mode,
                               int cert_verify_flags,
                               base::StringPiece origin_host,
                               base::StringPiece method,
                               const BoundNetLog& net_log,
                               QuicStreamRequest* request) {
   QuicServerId server_id(host_port_pair, privacy_mode);
   // TODO(rtenneti): crbug.com/498823 - delete active_sessions_.empty() checks.
   if (!active_sessions_.empty()) {
@@ skipping 733 matching lines @@
   // Since the session was active, there's no longer an
   // HttpStreamFactoryImpl::Job running which can mark it broken, unless the TCP
   // job also fails. So to avoid not using QUIC when we otherwise could, we mark
   // it as recently broken, which means that 0-RTT will be disabled but we'll
   // still race.
   http_server_properties_->MarkAlternativeServiceRecentlyBroken(
       alternative_service);
 }
 
 }  // namespace net