Add more out of line copy ctors for complex classes.

net/cert/signed_tree_head.cc

 // Copyright 2016 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/cert/signed_tree_head.h"
 
 #include <string.h>
 
 #include <ostream>
 
@@ skipping 11 matching lines @@
                                const DigitallySigned& signature,
                                const std::string& log_id)
     : version(version),
       timestamp(timestamp),
       tree_size(tree_size),
       signature(signature),
       log_id(log_id) {
   memcpy(this->sha256_root_hash, sha256_root_hash, kSthRootHashLength);
 }
 
+SignedTreeHead::SignedTreeHead(const SignedTreeHead& other) = default;
+
 SignedTreeHead::~SignedTreeHead() {}
 
 void PrintTo(const SignedTreeHead& sth, std::ostream* os) {
   (*os) << "{\n"
         << "\t\"version\": " << sth.version << ",\n"
         << "\t\"timestamp\": " << sth.timestamp << ",\n"
         << "\t\"tree_size\": " << sth.tree_size << ",\n"
         << "\t\"sha256_root_hash\": \""
         << base::HexEncode(sth.sha256_root_hash, kSthRootHashLength)
         << "\",\n\t\"log_id\": \""
         << base::HexEncode(sth.log_id.data(), sth.log_id.size()) << "\"\n"
         << "}";
 }
 
 }  // namespace ct
 }  // namespace net