Use constexpr TaskTraits constructor in chrome.

chrome/browser/web_applications/web_app_mac.mm

Index: chrome/browser/web_applications/web_app_mac.mm
diff --git a/chrome/browser/web_applications/web_app_mac.mm b/chrome/browser/web_applications/web_app_mac.mm
index ac3d5c80d4843ae2f092dab0c764b1c711c50127..45ebd5a380e25919bb6e2d999392c7a2a961db83 100644
--- a/chrome/browser/web_applications/web_app_mac.mm
+++ b/chrome/browser/web_applications/web_app_mac.mm
@@ -1027,8 +1027,7 @@ bool MaybeRebuildShortcut(const base::CommandLine& command_line) {
     return false;
 
   base::PostTaskWithTraitsAndReplyWithResult(
-      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                     base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::Bind(&RecordAppShimErrorAndBuildShortcutInfo,
                  command_line.GetSwitchValuePath(app_mode::kAppShimError)),
       base::Bind(&RebuildAppAndLaunch));