Use constexpr TaskTraits constructor in ui.

ui/events/ozone/device/device_manager_manual.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 "ui/events/ozone/device/device_manager_manual.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_enumerator.h"
 #include "base/location.h"
@@ skipping 46 matching lines @@
                       base::Bind(&DeviceManagerManual::OnWatcherEvent,
                                  weak_ptr_factory_.GetWeakPtr()))) {
     LOG(ERROR) << "Failed to start FilePathWatcher";
   }
 }
 
 void DeviceManagerManual::InitiateScanDevices() {
   std::vector<base::FilePath>* result = new std::vector<base::FilePath>();
   base::PostTaskWithTraitsAndReply(
       FROM_HERE,
-      base::TaskTraits()
-          .WithShutdownBehavior(
-              base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN)
-          .MayBlock(),
+      {base::MayBlock(), base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
       base::Bind(&ScanDevicesOnWorkerThread, result),
       base::Bind(&DeviceManagerManual::OnDevicesScanned,
                  weak_ptr_factory_.GetWeakPtr(), base::Owned(result)));
 }
 
 void DeviceManagerManual::OnDevicesScanned(
     std::vector<base::FilePath>* result) {
   std::set<base::FilePath> new_devices;
 
   // Reported newly added devices.
@@ skipping 26 matching lines @@
 void DeviceManagerManual::OnWatcherEvent(const base::FilePath& path,
                                          bool error) {
   // We need to restart watching if there's an error.
   if (error) {
     StartWatching();
   }
   InitiateScanDevices();
 }
 
 }  // namespace ui