Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/drive/write_on_cache_file.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/chromeos/drive/write_on_cache_file.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/task_scheduler/post_task.h"
 #include "base/threading/sequenced_worker_pool.h"
@@ skipping 22 matching lines @@
 void WriteOnCacheFileAfterOpenFile(
     const base::FilePath& drive_path,
     const WriteOnCacheFileCallback& file_io_task_callback,
     const FileOperationCallback& reply,
     FileError error,
     const base::FilePath& local_cache_path,
     const base::Closure& close_callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   base::PostTaskWithTraitsAndReply(
-      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                     base::TaskPriority::USER_BLOCKING),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::USER_BLOCKING},
       base::Bind(file_io_task_callback, error, local_cache_path),
       base::Bind(&RunCloseCallbackAndReplyTask, close_callback, reply, error));
 }
 
 }  // namespace
 
 void WriteOnCacheFile(FileSystemInterface* file_system,
                       const base::FilePath& path,
                       const std::string& mime_type,
                       const WriteOnCacheFileCallback& callback) {
@@ skipping 12 matching lines @@
   DCHECK(!reply.is_null());
 
   file_system->OpenFile(
       path,
       OPEN_OR_CREATE_FILE,
       mime_type,
       base::Bind(&WriteOnCacheFileAfterOpenFile, path, callback, reply));
 }
 
 }  // namespace drive