Use quiche string libraries in third_party/quic/core

gfe-relnote: n/a, no functional change
PiperOrigin-RevId: 285401547
Change-Id: Ice6d421ff7058fe2d47aee426d7634b6d403ee3f
diff --git a/quic/core/tls_client_handshaker.h b/quic/core/tls_client_handshaker.h
index 319cd17..0dd2320 100644
--- a/quic/core/tls_client_handshaker.h
+++ b/quic/core/tls_client_handshaker.h
@@ -14,6 +14,7 @@
 #include "net/third_party/quiche/src/quic/core/quic_crypto_stream.h"
 #include "net/third_party/quiche/src/quic/core/tls_handshaker.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_export.h"
+#include "net/third_party/quiche/src/common/platform/api/quiche_string_piece.h"
 
 namespace quic {
 
@@ -51,7 +52,8 @@
   size_t BufferSizeLimitForLevel(EncryptionLevel level) const override;
 
   // Override to drop initial keys if trying to write ENCRYPTION_HANDSHAKE data.
-  void WriteMessage(EncryptionLevel level, QuicStringPiece data) override;
+  void WriteMessage(EncryptionLevel level,
+                    quiche::QuicheStringPiece data) override;
 
   void AllowEmptyAlpnForTests() { allow_empty_alpn_for_tests_ = true; }