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

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index ae4e1a6e0faf7254c64936999ac1d4ee6533d8fd..9abb58ce4e8209d0b7cf54826aef402dfca5b6f1 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -1082,6 +1082,8 @@ void IOThread::InitializeNetworkSessionParamsFromGlobals(
   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);
@@ -1219,6 +1221,8 @@ void IOThread::ConfigureQuicGlobals(
         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,
@@ -1471,6 +1475,19 @@ bool IOThread::ShouldQuicCloseSessionsOnIpChange(
       "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.
+  return base::LowerCaseEqualsASCII(
+      GetVariationParam(quic_trial_params, "migrate_sessions_on_net_change"),
+      "true");
+#endif
+  return false;
+}
+
 size_t IOThread::GetQuicMaxPacketLength(
     const base::CommandLine& command_line,
     const VariationParameters& quic_trial_params) {