Pass TLS read/write secrets by absl::Span instead of a byte vector.

PiperOrigin-RevId: 445930737
diff --git a/quiche/quic/core/tls_client_handshaker.h b/quiche/quic/core/tls_client_handshaker.h
index d3c6312..21b6033 100644
--- a/quiche/quic/core/tls_client_handshaker.h
+++ b/quiche/quic/core/tls_client_handshaker.h
@@ -72,7 +72,7 @@
   void OnHandshakeDoneReceived() override;
   void OnNewTokenReceived(absl::string_view token) override;
   void SetWriteSecret(EncryptionLevel level, const SSL_CIPHER* cipher,
-                      const std::vector<uint8_t>& write_secret) override;
+                      absl::Span<const uint8_t> write_secret) override;
 
   // Override to drop initial keys if trying to write ENCRYPTION_HANDSHAKE data.
   void WriteMessage(EncryptionLevel level, absl::string_view data) override;