components: Add out-of-line copy ctors for complex classes.

components/update_client/crx_update_item.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 COMPONENTS_UPDATE_CLIENT_CRX_UPDATE_ITEM_H_
 #define COMPONENTS_UPDATE_CLIENT_CRX_UPDATE_ITEM_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 99 matching lines @@
   int error_category;
   int error_code;
   int extra_code1;
   int diff_error_category;
   int diff_error_code;
   int diff_extra_code1;
 
   std::vector<CrxDownloader::DownloadMetrics> download_metrics;
 
   CrxUpdateItem();
+  CrxUpdateItem(const CrxUpdateItem& other);
   ~CrxUpdateItem();
 
   // Function object used to find a specific component.
   class FindById {
    public:
     explicit FindById(const std::string& id) : id_(id) {}
 
     bool operator()(CrxUpdateItem* item) const { return item->id == id_; }
 
    private:
     const std::string& id_;
   };
 };
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_CRX_UPDATE_ITEM_H_