Remove QuicString wrapper for std::string

gfe-relnote: n/a (no functional change)
PiperOrigin-RevId: 238124961
Change-Id: I36e66a4326b4118d70effd356aef9734d2893763
diff --git a/quic/core/crypto/curve25519_key_exchange.cc b/quic/core/crypto/curve25519_key_exchange.cc
index 9c8e5ed..1400d0c 100644
--- a/quic/core/crypto/curve25519_key_exchange.cc
+++ b/quic/core/crypto/curve25519_key_exchange.cc
@@ -5,11 +5,11 @@
 #include "net/third_party/quiche/src/quic/core/crypto/curve25519_key_exchange.h"
 
 #include <cstdint>
+#include <string>
 
 #include "third_party/boringssl/src/include/openssl/curve25519.h"
 #include "net/third_party/quiche/src/quic/core/crypto/quic_random.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_ptr_util.h"
-#include "net/third_party/quiche/src/quic/platform/api/quic_string.h"
 
 namespace quic {
 namespace {