Add FLAGS_quic_crypto_server_config_default_has_chacha20, to allow

net/quic/crypto/quic_crypto_server_config.cc

 // Copyright 2013 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/crypto/quic_crypto_server_config.h"
 
 #include <stdlib.h>
 
 #include <algorithm>
 
@@ skipping 272 matching lines @@
     encoded_public_values.append(p256_public_value.data(),
                                  p256_public_value.size());
   }
 
   msg.set_tag(kSCFG);
   if (options.p256) {
     msg.SetTaglist(kKEXS, kC255, kP256, 0);
   } else {
     msg.SetTaglist(kKEXS, kC255, 0);
   }
-  if (FLAGS_quic_use_rfc7539 &&
-      ChaCha20Poly1305Rfc7539Encrypter::IsSupported()) {
-    msg.SetTaglist(kAEAD, kAESG, kCC12, kCC20, 0);
+  if (FLAGS_quic_crypto_server_config_default_has_chacha20) {
+    if (FLAGS_quic_use_rfc7539 &&
+        ChaCha20Poly1305Rfc7539Encrypter::IsSupported()) {
+      msg.SetTaglist(kAEAD, kAESG, kCC12, kCC20, 0);
+    } else {
+      msg.SetTaglist(kAEAD, kAESG, kCC12, 0);
+    }
   } else {
-    msg.SetTaglist(kAEAD, kAESG, kCC12, 0);
+    msg.SetTaglist(kAEAD, kAESG, 0);
   }
   msg.SetStringPiece(kPUBS, encoded_public_values);
 
   if (options.expiry_time.IsZero()) {
     const QuicWallTime now = clock->WallNow();
     const QuicWallTime expiry = now.Add(QuicTime::Delta::FromSeconds(
         60 * 60 * 24 * 180 /* 180 days, ~six months */));
     const uint64_t expiry_seconds = expiry.ToUNIXSeconds();
     msg.SetValue(kEXPY, expiry_seconds);
   } else {
@@ skipping 1499 matching lines @@
       priority(0),
       source_address_token_boxer(nullptr) {}
 
 QuicCryptoServerConfig::Config::~Config() {
   STLDeleteElements(&key_exchanges);
 }
 
 QuicCryptoProof::QuicCryptoProof() : certs(nullptr) {}
 QuicCryptoProof::~QuicCryptoProof() {}
 }  // namespace net