Use constexpr TaskTraits constructor in chrome.

chrome/browser/search/local_files_ntp_source.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/search/local_files_ntp_source.h"
 
 #include <memory>
 
 #if !defined(GOOGLE_CHROME_BUILD)
 
@@ skipping 98 matching lines @@
 void SendLocalFileResourceWithOrigin(
     const std::string& path,
     const std::string& origin,
     const content::URLDataSource::GotDataCallback& callback) {
   base::FilePath fullpath;
   PathService::Get(base::DIR_SOURCE_ROOT, &fullpath);
   fullpath = fullpath.AppendASCII(kBasePath).AppendASCII(path);
   content::URLDataSource::GotDataCallback wrapper =
       base::Bind(&CheckLocalIncludes, callback);
   base::PostTaskWithTraitsAndReplyWithResult(
-      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                     base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::Bind(&ReadFileAndReturn, fullpath),
       base::Bind(&CallbackWithLoadedResource, origin, wrapper));
 }
 
 }  // namespace local_ntp
 
 #endif  //  !defined(GOOGLE_CHROME_BUILD)