(For-try) Divide recursive Copy/Move into multiple async tasks

chrome/browser/media_gallery/linux/mtp_device_delegate_impl_linux.cc

 // Copyright (c) 2012 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_gallery/linux/mtp_device_delegate_impl_linux.h"
 
 #include "base/bind.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/sequenced_task_runner.h"
@@ skipping 115 matching lines @@
 PlatformFileError MTPDeviceDelegateImplLinux::CreateSnapshotFile(
     const FilePath& device_file_path,
     const FilePath& local_path,
     PlatformFileInfo* file_info) {
   if (!LazyInit())
     return base::PLATFORM_FILE_ERROR_FAILED;
 
   PlatformFileError error = GetFileInfo(device_file_path, file_info);
   if (error != base::PLATFORM_FILE_OK)
     return error;
+  if (file_info->is_directory)
+    return base::PLATFORM_FILE_ERROR_NOT_A_FILE;
 
   if (file_info->size <= 0 || file_info->size > kuint32max)
     return base::PLATFORM_FILE_ERROR_FAILED;
 
   scoped_refptr<MTPReadFileWorker> worker(new MTPReadFileWorker(
       device_handle_,
       GetDeviceRelativePath(device_path_, device_file_path.value()),
       file_info->size, local_path, media_task_runner_,
       &on_task_completed_event_, &on_shutdown_event_));
   worker->Run();
@@ skipping 41 matching lines @@
   return !device_handle_.empty();
 }
 
 void CreateMTPDeviceDelegate(const std::string& device_location,
                              base::SequencedTaskRunner* media_task_runner,
                              const CreateMTPDeviceDelegateCallback& cb) {
   cb.Run(new MTPDeviceDelegateImplLinux(device_location, media_task_runner));
 }
 
 }  // namespace chrome