Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/input_method/input_method_syncer.cc

Index: chrome/browser/chromeos/input_method/input_method_syncer.cc
diff --git a/chrome/browser/chromeos/input_method/input_method_syncer.cc b/chrome/browser/chromeos/input_method/input_method_syncer.cc
index 1d74f9dc40a987ee09bd84ddd54e1746f4218cfc..ccc30492636fa9e1fc346f74d9f6931df52279c4 100644
--- a/chrome/browser/chromeos/input_method/input_method_syncer.cc
+++ b/chrome/browser/chromeos/input_method/input_method_syncer.cc
@@ -242,8 +242,7 @@ void InputMethodSyncer::MergeSyncedPrefs() {
                                     preferred_languages_syncable,
                                     prefs::kLanguagePreferredLanguages));
   base::PostTaskWithTraitsAndReplyWithResult(
-      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                     base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::Bind(&CheckAndResolveLocales, languages),
       base::Bind(&InputMethodSyncer::FinishMerge, weak_factory_.GetWeakPtr()));
 }