Add IsResumption method to QUIC client handshakers

gfe-relnote: no behavior change: adding unused method
PiperOrigin-RevId: 279141655
Change-Id: Icfe08baf904b37a702c73c071334b11bb6cf2234
diff --git a/quic/core/tls_client_handshaker.h b/quic/core/tls_client_handshaker.h
index ad7939b..17b529e 100644
--- a/quic/core/tls_client_handshaker.h
+++ b/quic/core/tls_client_handshaker.h
@@ -40,6 +40,7 @@
   // From QuicCryptoClientStream::HandshakerDelegate
   bool CryptoConnect() override;
   int num_sent_client_hellos() const override;
+  bool IsResumption() const override;
   int num_scup_messages_received() const override;
   std::string chlo_hash() const override;