Use constexpr TaskTraits constructor in extensions.

extensions/browser/updater/update_install_shim.cc

Index: extensions/browser/updater/update_install_shim.cc
diff --git a/extensions/browser/updater/update_install_shim.cc b/extensions/browser/updater/update_install_shim.cc
index 110874db85e22830bdfa905abcccab45ad489758..04621b090db639e2cd0c6ef57d15581bdbed523d 100644
--- a/extensions/browser/updater/update_install_shim.cc
+++ b/extensions/browser/updater/update_install_shim.cc
@@ -80,8 +80,7 @@ UpdateInstallShim::~UpdateInstallShim() {}
 void UpdateInstallShim::RunCallbackOnUIThread(const base::FilePath& temp_dir) {
   if (callback_.is_null()) {
     base::PostTaskWithTraits(FROM_HERE,
-                             base::TaskTraits().MayBlock().WithPriority(
-                                 base::TaskPriority::BACKGROUND),
+                             {base::MayBlock(), base::TaskPriority::BACKGROUND},
                              base::Bind(base::IgnoreResult(&base::DeleteFile),
                                         temp_dir, true /*recursive */));
     return;