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

net/quic/quic_stream_factory.h

Index: net/quic/quic_stream_factory.h
diff --git a/net/quic/quic_stream_factory.h b/net/quic/quic_stream_factory.h
index b46854adb166fef9ba654b2da180f511d5abdde9..721532de1d0e1034ee57eecabd1a5c59638de0e8 100644
--- a/net/quic/quic_stream_factory.h
+++ b/net/quic/quic_stream_factory.h
@@ -103,6 +103,7 @@ class NET_EXPORT_PRIVATE QuicStreamRequest {
 // QuicChromiumClientSessions.
 class NET_EXPORT_PRIVATE QuicStreamFactory
     : public NetworkChangeNotifier::IPAddressObserver,
+      public NetworkChangeNotifier::NetworkObserver,
       public SSLConfigService::Observer,
       public CertDatabase::Observer {
  public:
@@ -138,6 +139,7 @@ class NET_EXPORT_PRIVATE QuicStreamFactory
       bool delay_tcp_race,
       bool store_server_configs_in_properties,
       bool close_sessions_on_ip_change,
+      bool migrate_sessions_on_net_change,
       const QuicTagVector& connection_options);
   ~QuicStreamFactory() override;
 
@@ -199,12 +201,39 @@ class NET_EXPORT_PRIVATE QuicStreamFactory
   // Delete all cached state objects in |crypto_config_|.
   void ClearCachedStatesInCryptoConfig();
 
+  // Helper method that creates and returns a DatagramClientSocket.
+  scoped_ptr<DatagramClientSocket> CreateDatagramClientSocket(
+      const QuicServerId& server_id,
+      const BoundNetLog& net_log);
+
+  // Helper method that configures a DatagramClientSocket.
+  // Returns net_error code.
+  int ConfigureDatagramClientSocket(
+      DatagramClientSocket* socket,
+      IPEndPoint addr,
+      NetworkChangeNotifier::NetworkHandle network);
+
+  // Helper method that initiates migration of active sessions away from
+  // |network| if possible, and if not, closes them. Migration is only
+  // attempted on active sessions; idle sessions are closed.
+  void MigrateOrCloseSessions(NetworkChangeNotifier::NetworkHandle);
+
   // NetworkChangeNotifier::IPAddressObserver methods:
 
   // Until the servers support roaming, close all connections when the local
   // IP address changes.
   void OnIPAddressChanged() override;
 
+  // NetworkChangeNotifier::NetworkObserver methods:
+  void OnNetworkConnected(
+      NetworkChangeNotifier::NetworkHandle network) override;
+  void OnNetworkDisconnected(
+      NetworkChangeNotifier::NetworkHandle network) override;
+  void OnNetworkSoonToDisconnect(
+      NetworkChangeNotifier::NetworkHandle network) override;
+  void OnNetworkMadeDefault(
+      NetworkChangeNotifier::NetworkHandle network) override;
+
   // SSLConfigService::Observer methods:
 
   // We perform the same flushing as described above when SSL settings change.
@@ -441,6 +470,10 @@ class NET_EXPORT_PRIVATE QuicStreamFactory
   // Set if all sessions should be closed when any local IP address changes.
   const bool close_sessions_on_ip_change_;
 
+  // Set if migration should be attempted on active sessions when primary
+  // interface changes.
+  const bool migrate_sessions_on_net_change_;
+
   // Each profile will (probably) have a unique port_seed_ value.  This value
   // is used to help seed a pseudo-random number generator (PortSuggester) so
   // that we consistently (within this profile) suggest the same ephemeral