Add support of serving SCT on the server side in QUIC, gated by QUIC_VERSION_30.

net/quic/crypto/proof_source_chromium_openssl.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/proof_source_chromium.h"
 
 #include <openssl/digest.h>
 #include <openssl/evp.h>
 #include <openssl/rsa.h>
 
@@ skipping 54 matching lines @@
     return false;
   }
   return true;
 }
 
 bool ProofSourceChromium::GetProof(const IPAddressNumber& server_ip,
                                    const string& hostname,
                                    const string& server_config,
                                    bool ecdsa_ok,
                                    const vector<string>** out_certs,
-                                   string* out_signature) {
+                                   string* out_signature,
+                                   string* out_leaf_cert_sct) {
   DCHECK(private_key_.get()) << " this: " << this;
 
   crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
   crypto::ScopedEVP_MD_CTX sign_context(EVP_MD_CTX_create());
   EVP_PKEY_CTX* pkey_ctx;
   if (!EVP_DigestSignInit(sign_context.get(), &pkey_ctx, EVP_sha256(), nullptr,
                           private_key_->key()) ||
       !EVP_PKEY_CTX_set_rsa_padding(pkey_ctx, RSA_PKCS1_PSS_PADDING) ||
       !EVP_PKEY_CTX_set_rsa_pss_saltlen(pkey_ctx, -1) ||
       !EVP_DigestSignUpdate(sign_context.get(), reinterpret_cast<const uint8*>(
@@ skipping 19 matching lines @@
   signature.resize(len);
   out_signature->assign(reinterpret_cast<const char*>(&signature[0]),
                         signature.size());
   *out_certs = &certificates_;
   VLOG(1) << "signature: "
           << base::HexEncode(out_signature->data(), out_signature->size());
   return true;
 }
 
 }  // namespace net