Use constexpr TaskTraits constructor in chrome.

chrome/browser/android/offline_pages/request_coordinator_factory.cc

 // Copyright 2016 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/android/offline_pages/request_coordinator_factory.h"
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
@@ skipping 50 matching lines @@
 
   // Determines which offliner to use based on flag.
   if (ShouldUseNewBackgroundLoader()) {
     offliner.reset(new BackgroundLoaderOffliner(context, policy.get(), model));
   } else {
     offliner.reset(new PrerenderingOffliner(context, policy.get(), model));
   }
 
   scoped_refptr<base::SequencedTaskRunner> background_task_runner =
       base::CreateSequencedTaskRunnerWithTraits(
-          base::TaskTraits().MayBlock().WithPriority(
-              base::TaskPriority::BACKGROUND));
+          {base::MayBlock(), base::TaskPriority::BACKGROUND});
   Profile* profile = Profile::FromBrowserContext(context);
   base::FilePath queue_store_path =
       profile->GetPath().Append(chrome::kOfflinePageRequestQueueDirname);
 
   std::unique_ptr<RequestQueueStoreSQL> queue_store(
       new RequestQueueStoreSQL(background_task_runner, queue_store_path));
   std::unique_ptr<RequestQueue> queue(new RequestQueue(std::move(queue_store)));
   std::unique_ptr<Scheduler>
       scheduler(new android::BackgroundSchedulerBridge());
   net::NetworkQualityEstimator::NetworkQualityProvider*
       network_quality_estimator =
           UINetworkQualityEstimatorServiceFactory::GetForProfile(profile);
   RequestCoordinator* request_coordinator = new RequestCoordinator(
       std::move(policy), std::move(offliner), std::move(queue),
       std::move(scheduler), network_quality_estimator);
 
   DownloadNotifyingObserver::CreateAndStartObserving(
       request_coordinator,
       base::MakeUnique<android::OfflinePageNotificationBridge>());
 
   return request_coordinator;
 }
 
 }  // namespace offline_pages