Use constexpr TaskTraits constructor in chrome.

chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
index 70c923227ebc111aede78cd04e441983a41c5460..ed43fa46bf9eadb73d6486b4c8a1f19cc292e398 100644
--- a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
@@ -269,8 +269,7 @@ void GaiaScreenHandler::DisableRestrictiveProxyCheckForTest() {
 
 void GaiaScreenHandler::LoadGaia(const GaiaContext& context) {
   base::PostTaskWithTraitsAndReplyWithResult(
-      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                     base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::Bind(&version_loader::GetVersion, version_loader::VERSION_SHORT),
       base::Bind(&GaiaScreenHandler::LoadGaiaWithVersion,
                  weak_factory_.GetWeakPtr(), context));