Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/external_metrics.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/chromeos/external_metrics.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <memory>
@@ skipping 155 matching lines @@
   return samples.size();
 }
 
 void ExternalMetrics::CollectEventsAndReschedule() {
   CollectEvents();
   ScheduleCollector();
 }
 
 void ExternalMetrics::ScheduleCollector() {
   base::PostDelayedTaskWithTraits(
-      FROM_HERE,
-      base::TaskTraits().MayBlock().WithPriority(
-          base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::BindOnce(&chromeos::ExternalMetrics::CollectEventsAndReschedule,
                      this),
       kExternalMetricsCollectionInterval);
 }
 
 }  // namespace chromeos