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

chrome/browser/media_galleries/media_folder_finder.cc

 // 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.
 
 #include "chrome/browser/media_galleries/media_folder_finder.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 153 matching lines @@
   base::FilePath platform_root = GetPlatformSpecificDefaultScanRoot();
   if (!platform_root.empty())
     roots.push_back(platform_root);
   callback.Run(roots);
 }
 
 }  // namespace
 
 MediaFolderFinder::WorkerReply::WorkerReply() {}
 
+MediaFolderFinder::WorkerReply::WorkerReply(const WorkerReply& other) = default;
+
 MediaFolderFinder::WorkerReply::~WorkerReply() {}
 
 // The Worker is created on the UI thread, but does all its work on a blocking
 // SequencedTaskRunner.
 class MediaFolderFinder::Worker {
  public:
   explicit Worker(const std::vector<base::FilePath>& graylisted_folders);
   ~Worker();
 
   // Scans |path| and return the results.
@@ skipping 256 matching lines @@
 
   if (!IsEmptyScanResult(reply.scan_result))
     results_[path] = reply.scan_result;
 
   // Push new folders to the |folders_to_scan_| in reverse order.
   std::copy(reply.new_folders.rbegin(), reply.new_folders.rend(),
             std::back_inserter(folders_to_scan_));
 
   ScanFolder();
 }