Add more out of line copy ctors for complex classes.

net/cert/signed_tree_head.h

 // Copyright 2014 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.
 
 #ifndef NET_CERT_SIGNED_TREE_HEAD_H_
 #define NET_CERT_SIGNED_TREE_HEAD_H_
 
 #include <stdint.h>
 
 #include <iosfwd>
@@ skipping 18 matching lines @@
   // RFC6962-bis to use separate versions, so using a separate scheme here.
   enum Version { V1 = 0, };
 
   SignedTreeHead();
   SignedTreeHead(Version version,
                  const base::Time& timestamp,
                  uint64_t tree_size,
                  const char sha256_root_hash[kSthRootHashLength],
                  const DigitallySigned& signature,
                  const std::string& log_id);
+  SignedTreeHead(const SignedTreeHead& other);
   ~SignedTreeHead();
 
   Version version;
   base::Time timestamp;
   uint64_t tree_size;
   char sha256_root_hash[kSthRootHashLength];
   DigitallySigned signature;
 
   // Added in RFC6962-bis, Appendix A. Needed to identify which log
   // this STH belongs to.
   std::string log_id;
 };
 
 NET_EXPORT void PrintTo(const SignedTreeHead& sth, std::ostream* os);
 
 }  // namespace ct
 
 }  // namespace net
 
 #endif