Use constexpr TaskTraits constructor in chromeos.

chromeos/settings/timezone_settings.cc

Index: chromeos/settings/timezone_settings.cc
diff --git a/chromeos/settings/timezone_settings.cc b/chromeos/settings/timezone_settings.cc
index 9c3a371747f1cd33fd6c2d18bc673047e62be959..a413459e55ffa69b54dd6c993b42b5b5c642a1eb 100644
--- a/chromeos/settings/timezone_settings.cc
+++ b/chromeos/settings/timezone_settings.cc
@@ -391,13 +391,10 @@ void TimezoneSettingsImpl::SetTimezone(const icu::TimeZone& timezone) {
   VLOG(1) << "Setting timezone to " << id;
   // It's safe to change the timezone config files in the background as the
   // following operations don't depend on the completion of the config change.
-  base::PostTaskWithTraits(
-      FROM_HERE, base::TaskTraits()
-                     .WithShutdownBehavior(
-                         base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN)
-                     .WithPriority(base::TaskPriority::BACKGROUND)
-                     .MayBlock(),
-      base::Bind(&SetTimezoneIDFromString, id));
+  base::PostTaskWithTraits(FROM_HERE,
+                           {base::MayBlock(), base::TaskPriority::BACKGROUND,
+                            base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
+                           base::Bind(&SetTimezoneIDFromString, id));
   icu::TimeZone::setDefault(*known_timezone);
   for (auto& observer : observers_)
     observer.TimezoneChanged(*known_timezone);