Moves QuicTag typedefs, and QuicTag utility methods to quic_tag.{h,cc}. No behavior change.

net/quic/test_tools/crypto_test_utils_test.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/test_tools/crypto_test_utils.h"
 
 #include "net/quic/core/crypto/crypto_server_config_protobuf.h"
 #include "net/quic/core/quic_utils.h"
 #include "net/quic/test_tools/mock_clock.h"
 #include "net/test/gtest_util.h"
@@ skipping 134 matching lines @@
   QuicVersion version(AllSupportedVersions().front());
   // clang-format off
   CryptoHandshakeMessage inchoate_chlo = CryptoTestUtils::Message(
     "CHLO",
     "PDMD", "X509",
     "AEAD", "AESG",
     "KEXS", "C255",
     "COPT", "SREJ",
     "PUBS", pub_hex.c_str(),
     "NONC", nonce_hex.c_str(),
-    "VER\0", QuicUtils::TagToString(QuicVersionToQuicTag(version)).c_str(),
+    "VER\0", QuicTagToString(QuicVersionToQuicTag(version)).c_str(),
     "$padding", static_cast<int>(kClientHelloMinimumSize),
     nullptr);
   // clang-format on
 
   CryptoTestUtils::GenerateFullCHLO(inchoate_chlo, &crypto_config, server_ip,
                                     client_addr, version, &clock, signed_config,
                                     &compressed_certs_cache, &full_chlo);
   // Verify that full_chlo can pass crypto_config's verification.
   ShloVerifier shlo_verifier(&crypto_config, server_ip, client_addr, &clock,
                              signed_config, &compressed_certs_cache);
   crypto_config.ValidateClientHello(
       full_chlo, client_addr.address(), server_ip, version, &clock,
       signed_config, shlo_verifier.GetValidateClientHelloCallback());
 }
 
 }  // namespace test
 }  // namespace net