Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/app_mode/startup_app_launcher.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/app_mode/startup_app_launcher.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/json/json_file_value_serializer.h"
@@ skipping 101 matching lines @@
   // is ready for sure.
   wait_for_crx_update_ = true;
   KioskAppManager::Get()->UpdateExternalCache();
 }
 
 void StartupAppLauncher::StartLoadingOAuthFile() {
   delegate_->OnLoadingOAuthFile();
 
   KioskOAuthParams* auth_params = new KioskOAuthParams();
   base::PostTaskWithTraitsAndReply(
-      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                     base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::Bind(&StartupAppLauncher::LoadOAuthFileAsync, auth_params),
       base::Bind(&StartupAppLauncher::OnOAuthFileLoaded, AsWeakPtr(),
                  base::Owned(auth_params)));
 }
 
 // static.
 void StartupAppLauncher::LoadOAuthFileAsync(KioskOAuthParams* auth_params) {
   int error_code = JSONFileValueDeserializer::JSON_NO_ERROR;
   std::string error_msg;
   base::FilePath user_data_dir;
@@ skipping 457 matching lines @@
   // Skip copying meta data from the current installed primary app when
   // there is a pending update.
   if (PrimaryAppHasPendingUpdate())
     return;
 
   KioskAppManager::Get()->ClearAppData(app_id_);
   KioskAppManager::Get()->UpdateAppDataFromProfile(app_id_, profile_, NULL);
 }
 
 }   // namespace chromeos