Add following helper methods to track successful QUIC client port migrations:

net/quic/quic_connection.h

Index: net/quic/quic_connection.h
diff --git a/net/quic/quic_connection.h b/net/quic/quic_connection.h
index fec6c6882e579b033e43a916924a0596672c69d7..52ee6bb65d07d3b01afc52e5d7d917489dc864cf 100644
--- a/net/quic/quic_connection.h
+++ b/net/quic/quic_connection.h
@@ -306,7 +306,7 @@ class NET_EXPORT_PRIVATE QuicConnection
   // Do any work which logically would be done in OnPacket but can not be
   // safely done until the packet is validated.  Returns true if the packet
   // can be handled, false otherwise.
-  bool ProcessValidatedPacket();
+  virtual bool ProcessValidatedPacket();
 
   // The version of the protocol this connection is using.
   QuicVersion version() const { return framer_.version(); }
@@ -512,6 +512,16 @@ class NET_EXPORT_PRIVATE QuicConnection
 
   QuicPacketWriter* writer() { return writer_; }
 
+  bool peer_port_changed() const { return peer_port_changed_; }
+
+  const QuicReceivedPacketManager& received_packet_manager() {
+    return received_packet_manager_;
+  }
+
+  QuicPacketSequenceNumber sequence_number_of_last_sent_packet() const {
+    return sequence_number_of_last_sent_packet_;
+  }
+
  private:
   friend class test::QuicConnectionPeer;