Killing off QUICv12, including cleaning out all of the code for handling

net/quic/crypto/quic_crypto_client_config.cc

Index: net/quic/crypto/quic_crypto_client_config.cc
diff --git a/net/quic/crypto/quic_crypto_client_config.cc b/net/quic/crypto/quic_crypto_client_config.cc
index 95d17265a00933fb5903aa8234b35ae78a18a43e..ac6480a377ef989528aff53080ad28986839be99 100644
--- a/net/quic/crypto/quic_crypto_client_config.cc
+++ b/net/quic/crypto/quic_crypto_client_config.cc
@@ -335,8 +335,6 @@ void QuicCryptoClientConfig::FillInchoateClientHello(
   if (CryptoUtils::IsValidSNI(server_hostname)) {
     out->SetStringPiece(kSNI, server_hostname);
   }
-  // TODO(rch): Remove once we remove QUIC_VERSION_12.
-  out->SetValue(kVERS, static_cast<uint16>(0));
   out->SetValue(kVER, QuicVersionToQuicTag(preferred_version));
 
   if (!cached->source_address_token().empty()) {
@@ -648,8 +646,8 @@ QuicErrorCode QuicCryptoClientConfig::ProcessServerHello(
 
   const QuicTag* supported_version_tags;
   size_t num_supported_versions;
-  // TODO(rch): Once QUIC_VERSION_12 is removed, then make it a failure
-  // if the server does not have a version list.
+
+  // TODO(rch): Make it a failure if the server does not have a version list.
   if (server_hello.GetTaglist(kVER, &supported_version_tags,
                               &num_supported_versions) == QUIC_NO_ERROR) {
     if (!negotiated_versions.empty()) {