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

chrome/browser/sync_file_system/sync_file_metadata.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 "chrome/browser/sync_file_system/sync_file_metadata.h"
 
 using sync_file_system::SyncFileType;
 
 namespace sync_file_system {
 
 SyncFileMetadata::SyncFileMetadata()
     : file_type(sync_file_system::SYNC_FILE_TYPE_UNKNOWN),
       size(-1) {
 }
 
 SyncFileMetadata::SyncFileMetadata(SyncFileType file_type,
                                    int64_t size,
                                    const base::Time& last_modified)
     : file_type(file_type), size(size), last_modified(last_modified) {}
 
 SyncFileMetadata::~SyncFileMetadata() {}
 
 bool SyncFileMetadata::operator==(const SyncFileMetadata& that) const {
   return file_type == that.file_type &&
          size == that.size &&
          last_modified == that.last_modified;
 }
 
 LocalFileSyncInfo::LocalFileSyncInfo() {}
+LocalFileSyncInfo::LocalFileSyncInfo(const LocalFileSyncInfo& other) = default;
 LocalFileSyncInfo::~LocalFileSyncInfo() {}
 
 }  // namespace sync_file_system