Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/file_manager/snapshot_manager.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/chromeos/file_manager/snapshot_manager.h"
 
 #include "base/bind.h"
 #include "base/sys_info.h"
 #include "base/task_scheduler/post_task.h"
 #include "chrome/browser/chromeos/file_manager/app_id.h"
@@ skipping 30 matching lines @@
     const GetNecessaryFreeSpaceCallback& callback,
     base::File::Error result,
     const base::File::Info& file_info) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
   if (result != base::File::FILE_OK) {
     callback.Run(-1);
     return;
   }
 
   base::PostTaskWithTraitsAndReplyWithResult(
-      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                     base::TaskPriority::USER_BLOCKING),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::USER_BLOCKING},
       base::Bind(&ComputeSpaceNeedToBeFreedAfterGetMetadataAsync, path,
                  file_info.size),
       callback);
 }
 
 // Part of ComputeSpaceNeedToBeFreed.
 void GetMetadataOnIOThread(const base::FilePath& path,
                            scoped_refptr<storage::FileSystemContext> context,
                            const storage::FileSystemURL& url,
                            const GetNecessaryFreeSpaceCallback& callback) {
@@ skipping 143 matching lines @@
   if (result != base::File::FILE_OK) {
     callback.Run(base::FilePath());
     return;
   }
 
   file_refs_.push_back(FileReferenceWithSizeInfo(file_ref, file_info.size));
   callback.Run(platform_path);
 }
 
 }  // namespace file_manager