Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc

Index: chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
diff --git a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
index 293b05b996d542650c85f3b8a5615cf9af7583b9..957415f6713822fdb61615dad147678364476f11 100644
--- a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
+++ b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc
@@ -961,7 +961,7 @@ void WallpaperManager::OnDeviceWallpaperExists(const AccountId& account_id,
                                                bool exist) {
   if (exist) {
     base::PostTaskWithTraitsAndReplyWithResult(
-        FROM_HERE, base::TaskTraits().MayBlock(),
+        FROM_HERE, {base::MayBlock()},
         base::Bind(&CheckDeviceWallpaperMatchHash, GetDeviceWallpaperFilePath(),
                    hash),
         base::Bind(&WallpaperManager::OnCheckDeviceWallpaperMatchHash,
@@ -989,7 +989,7 @@ void WallpaperManager::OnDeviceWallpaperDownloaded(const AccountId& account_id,
   }
 
   base::PostTaskWithTraitsAndReplyWithResult(
-      FROM_HERE, base::TaskTraits().MayBlock(),
+      FROM_HERE, {base::MayBlock()},
       base::Bind(&CheckDeviceWallpaperMatchHash, GetDeviceWallpaperFilePath(),
                  hash),
       base::Bind(&WallpaperManager::OnCheckDeviceWallpaperMatchHash,
@@ -1285,7 +1285,7 @@ bool WallpaperManager::SetDeviceWallpaperIfApplicable(
     // Check if the device wallpaper exists and matches the hash. If so, use it
     // directly. Otherwise download it first.
     base::PostTaskWithTraitsAndReplyWithResult(
-        FROM_HERE, base::TaskTraits().MayBlock(),
+        FROM_HERE, {base::MayBlock()},
         base::Bind(&base::PathExists, GetDeviceWallpaperFilePath()),
         base::Bind(&WallpaperManager::OnDeviceWallpaperExists,
                    weak_factory_.GetWeakPtr(), account_id, url, hash));