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

net/quic/quic_connection.h

 // 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.
 //
 // The entity that handles framing writes for a Quic client or server.
 // Each QuicSession will have a connection associated with it.
 //
 // On the server side, the Dispatcher handles the raw reads, and hands off
 // packets via ProcessUdpPacket for framing and processing.
 //
@@ skipping 371 matching lines @@
 
   // Called when an error occurs while attempting to write a packet to the
   // network.
   void OnWriteError(int error_code);
 
   // If the socket is not blocked, writes queued packets.
   void WriteIfNotBlocked();
 
   // Set the packet writer.
   void SetQuicPacketWriter(QuicPacketWriter* writer, bool owns_writer) {
+    DCHECK(writer != nullptr);
+    if (writer_ != nullptr && owns_writer_) {
+      delete writer_;
+    }
     writer_ = writer;
     owns_writer_ = owns_writer;
   }
 
   // Set self address.
   void SetSelfAddress(IPEndPoint address) { self_address_ = address; }
 
   // The version of the protocol this connection is using.
   QuicVersion version() const { return framer_.version(); }
 
@@ skipping 96 matching lines @@
   bool HasQueuedData() const;
 
   // Sets the overall and idle state connection timeouts.
   void SetNetworkTimeouts(QuicTime::Delta overall_timeout,
                           QuicTime::Delta idle_timeout);
 
   // If the connection has timed out, this will close the connection.
   // Otherwise, it will reschedule the timeout alarm.
   void CheckForTimeout();
 
-  // Sends a ping, and resets the ping alarm.
+  // Called when the ping alarm fires. Causes a ping frame to be sent only
+  // if the retransmission alarm is not running.
+  void OnPingTimeout();
+
+  // Sends a ping frame.
   void SendPing();
 
   // Sets up a packet with an QuicAckFrame and sends it out.
   void SendAck();
 
   // Called when an RTO fires.  Resets the retransmission alarm if there are
   // remaining unacked packets.
   void OnRetransmissionTimeout();
 
   // Called when a data packet is sent. Starts an alarm if the data sent in
@@ skipping 462 matching lines @@
 
   // If true, multipath is enabled for this connection.
   bool multipath_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicConnection);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_CONNECTION_H_