Delete unused, unimplemented CheckForAddressMigration declaration.

net/quic/core/quic_connection.h

Index: net/quic/core/quic_connection.h
diff --git a/net/quic/core/quic_connection.h b/net/quic/core/quic_connection.h
index 4198fc5d597aba62cc152a6984cdfcc507600a12..456eec5fe609e4af22a2e99abe7dc1fd17512b57 100644
--- a/net/quic/core/quic_connection.h
+++ b/net/quic/core/quic_connection.h
@@ -833,11 +833,6 @@ class NET_EXPORT_PRIVATE QuicConnection
   // Sets the MTU discovery alarm if necessary.
   void MaybeSetMtuAlarm();
 
-  // On arrival of a new packet, checks to see if the socket addresses have
-  // changed since the last packet we saw on this connection.
-  void CheckForAddressMigration(const IPEndPoint& self_address,
-                                const IPEndPoint& peer_address);
-
   HasRetransmittableData IsRetransmittable(const SerializedPacket& packet);
   bool IsTerminationPacket(const SerializedPacket& packet);