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

chrome/browser/sync_file_system/drive_backend/tracker_id_set.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 CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_TRACKER_ID_SET_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_TRACKER_ID_SET_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <set>
 
 
 namespace sync_file_system {
 namespace drive_backend {
 
 class FileTracker;
 
 class TrackerIDSet {
  public:
   typedef std::set<int64_t> RawTrackerIDSet;
   typedef RawTrackerIDSet::iterator iterator;
   typedef RawTrackerIDSet::const_iterator const_iterator;
 
   TrackerIDSet();
+  TrackerIDSet(const TrackerIDSet& other);
   ~TrackerIDSet();
 
   bool has_active() const { return !!active_tracker_; }
   void Insert(const FileTracker& tracker);
   void InsertActiveTracker(int64_t tracker_id);
   void InsertInactiveTracker(int64_t tracker_id);
   void Erase(int64_t tracker_id);
   void Activate(int64_t tracker_id);
   void Deactivate(int64_t tracker_id);
 
   int64_t active_tracker() const { return active_tracker_; }
   const RawTrackerIDSet& tracker_set() const { return tracker_ids_; }
 
   iterator begin() { return tracker_ids_.begin(); }
   iterator end() { return tracker_ids_.end(); }
   const_iterator begin() const { return tracker_ids_.begin(); }
   const_iterator end() const { return tracker_ids_.end(); }
   bool empty() const { return tracker_ids_.empty(); }
   size_t size() const { return tracker_ids_.size(); }
 
  private:
   int64_t active_tracker_;
   RawTrackerIDSet tracker_ids_;
 };
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_TRACKER_ID_SET_H_