Migrates QUIC sessions to a new network when old network is (about to be) disconnected.

chrome/browser/io_thread.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 "chrome/browser/io_thread.h"
 
 #include <vector>
 
 #include "base/base64.h"
 #include "base/bind.h"
@@ skipping 1089 matching lines @@
   globals.quic_delay_tcp_race.CopyToIfSet(&params->quic_delay_tcp_race);
   globals.enable_quic_port_selection.CopyToIfSet(
       &params->enable_quic_port_selection);
   globals.quic_max_packet_length.CopyToIfSet(&params->quic_max_packet_length);
   globals.quic_user_agent_id.CopyToIfSet(&params->quic_user_agent_id);
   globals.quic_supported_versions.CopyToIfSet(
       &params->quic_supported_versions);
   params->quic_connection_options = globals.quic_connection_options;
   globals.quic_close_sessions_on_ip_change.CopyToIfSet(
       &params->quic_close_sessions_on_ip_change);
-
+  globals.quic_migrate_sessions_on_net_change.CopyToIfSet(
+      &params->quic_migrate_sessions_on_net_change);
   globals.origin_to_force_quic_on.CopyToIfSet(
       &params->origin_to_force_quic_on);
   params->enable_user_alternate_protocol_ports =
       globals.enable_user_alternate_protocol_ports;
 }
 
 base::TimeTicks IOThread::creation_time() const {
   return creation_time_;
 }
 
@@ skipping 114 matching lines @@
     }
     float packet_loss_threshold = GetQuicPacketLossThreshold(quic_trial_params);
     if (packet_loss_threshold != 0)
       globals->quic_packet_loss_threshold.set(packet_loss_threshold);
     globals->enable_quic_port_selection.set(
         ShouldEnableQuicPortSelection(command_line));
     globals->quic_connection_options =
         GetQuicConnectionOptions(command_line, quic_trial_params);
     globals->quic_close_sessions_on_ip_change.set(
         ShouldQuicCloseSessionsOnIpChange(quic_trial_params));
+    globals->quic_migrate_sessions_on_net_change.set(
+        ShouldQuicMigrateSessionsOnNetChange(quic_trial_params));
   }
 
   size_t max_packet_length = GetQuicMaxPacketLength(command_line,
                                                     quic_trial_params);
   if (max_packet_length != 0) {
     globals->quic_max_packet_length.set(max_packet_length);
   }
 
   std::string quic_user_agent_id = chrome::GetChannelString();
   if (!quic_user_agent_id.empty())
@@ skipping 221 matching lines @@
       GetVariationParam(quic_trial_params, "delay_tcp_race"), "true");
 }
 
 bool IOThread::ShouldQuicCloseSessionsOnIpChange(
     const VariationParameters& quic_trial_params) {
   return base::LowerCaseEqualsASCII(
       GetVariationParam(quic_trial_params, "close_sessions_on_ip_change"),
       "true");
 }
 
+bool IOThread::ShouldQuicMigrateSessionsOnNetChange(
+    const VariationParameters& quic_trial_params) {
+#if defined(OS_ANDROID)
+  &&base::android::BuildInfo::GetInstance()->sdk_int() >=
+      base::android::SDK_VERSION_LOLLIPOP
+      // Migration only implemented for Android versions >= L.

[Ryan Hamilton, 2015/11/17 14:37:10]

I was thinking about this. This code is here because NetworkChangeNotifier only
implements the high-resolution events on Lollipop, right? In that case, I think
NetworkChangeNotifier should have a method like SupportsHighResolutinEvents (or
whatever) and QuicStreamFactory should query that...

[Jana, 2015/11/18 04:31:41]

Yeah -- I hadn't done that yet. But you're right that if we do this in the
stream_factory, we don't need to do it here. I like your API, but I'm doing this
in the quic_stream_factory for now. Paul, I can add this API; do you think this
is a reasonable change to NetworkChangeNotifier?

[pauljensen, 2015/11/18 17:24:23]

ya, adding a NetworkChangeNotifier API for this SGTM.  I was going to propose
adding a net error code return value from the NCN::GetDefaultNetwork API: 
https://codereview.chromium.org/1416213003/diff/1/net/base/network_change_not...
but having a more general API seems like a good idea.

[Jana, 2015/11/18 21:44:17]

Yeah, I think this belongs in the NetworkChangeNotifier, because we'd want to
make a decision about which notifier to register for based on this query. I'll
get this in.

[Ryan Hamilton, 2015/11/18 22:23:35]

One idea might be to have NetworkChangeNotifier::AddNetworkObserver() return a
bool, which is false if the NetworkObserver is not supported?

[Jana, 2015/11/21 02:21:22]

Ongoing in https://codereview.chromium.org/1454313002/

+      return base::LowerCaseEqualsASCII(
+          GetVariationParam(quic_trial_params,
+                            "migrate_sessions_on_net_change"),
+          "true");
+#endif
+  return false;
+}

[Ryan Hamilton, 2015/11/17 04:57:27]

Since this code is conditional, I'm surprised the tests are not conditional on
#if android.

[Jana, 2015/11/18 04:31:41]

code's not conditional anymore, so tests should be fine.

+
 size_t IOThread::GetQuicMaxPacketLength(
     const base::CommandLine& command_line,
     const VariationParameters& quic_trial_params) {
   if (command_line.HasSwitch(switches::kQuicMaxPacketLength)) {
     unsigned value;
     if (!base::StringToUint(
             command_line.GetSwitchValueASCII(switches::kQuicMaxPacketLength),
             &value)) {
       return 0;
     }
@@ skipping 158 matching lines @@
   globals->proxy_script_fetcher_url_request_job_factory = job_factory.Pass();
 
   context->set_job_factory(
       globals->proxy_script_fetcher_url_request_job_factory.get());
 
   // TODO(rtenneti): We should probably use HttpServerPropertiesManager for the
   // system URLRequestContext too. There's no reason this should be tied to a
   // profile.
   return context;
 }