Make ClientDemandsX509Proof a free function

gfe-relnote: n/a Code motion only.
PiperOrigin-RevId: 238704660
Change-Id: I521a8b916eb6e1a0b6e2a198d42a0561753ff266

quic/core/crypto/quic_crypto_server_config.cc

diff --git a/quic/core/crypto/quic_crypto_server_config.cc b/quic/core/crypto/quic_crypto_server_config.cc
index 56de827..cb5ad45 100644
--- a/quic/core/crypto/quic_crypto_server_config.cc
+++ b/quic/core/crypto/quic_crypto_server_config.cc
@@ -95,6 +95,23 @@
   }
 };
 
+// Returns true if the PDMD field from the client hello demands an X509
+// certificate.
+bool ClientDemandsX509Proof(const CryptoHandshakeMessage& client_hello) {
+  QuicTagVector their_proof_demands;
+
+  if (client_hello.GetTaglist(kPDMD, &their_proof_demands) != QUIC_NO_ERROR) {
+    return false;
+  }
+
+  for (const QuicTag tag : their_proof_demands) {
+    if (tag == kX509) {
+      return true;
+    }
+  }
+  return false;
+}
+
 }  // namespace
 
 // static
@@ -1931,22 +1948,6 @@
   return CryptoUtils::ComputeLeafCertHash(certs.at(0)) == hash_from_client;
 }
 
-bool QuicCryptoServerConfig::ClientDemandsX509Proof(
-    const CryptoHandshakeMessage& client_hello) const {
-  QuicTagVector their_proof_demands;
-
-  if (client_hello.GetTaglist(kPDMD, &their_proof_demands) != QUIC_NO_ERROR) {
-    return false;
-  }
-
-  for (const QuicTag tag : their_proof_demands) {
-    if (tag == kX509) {
-      return true;
-    }
-  }
-  return false;
-}
-
 bool QuicCryptoServerConfig::IsNextConfigReady(QuicWallTime now) const {
   if (GetQuicReloadableFlag(quic_fix_config_rotation)) {
     QUIC_RELOADABLE_FLAG_COUNT(quic_fix_config_rotation);

quic/core/crypto/quic_crypto_server_config.h

diff --git a/quic/core/crypto/quic_crypto_server_config.h b/quic/core/crypto/quic_crypto_server_config.h
index 0d7037f..54ddf76 100644
--- a/quic/core/crypto/quic_crypto_server_config.h
+++ b/quic/core/crypto/quic_crypto_server_config.h
@@ -682,10 +682,6 @@
       const CryptoHandshakeMessage& client_hello,
       const std::vector<std::string>& certs) const;
 
-  // Returns true if the PDMD field from the client hello demands an X509
-  // certificate.
-  bool ClientDemandsX509Proof(const CryptoHandshakeMessage& client_hello) const;
-
   // Callback to receive the results of ProofSource::GetProof.  Note: this
   // callback has no cancellation support, since the lifetime of the ProofSource
   // is controlled by this object via unique ownership.  If that ownership