Use constexpr TaskTraits constructor in extensions.

extensions/browser/updater/update_data_provider.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/browser/updater/update_data_provider.h"
 
 #include "base/base64.h"
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
@@ skipping 42 matching lines @@
     info->installer = new UpdateInstallShim(
         id, extension->path(),
         base::Bind(&UpdateDataProvider::RunInstallCallback, this));
   }
 }
 
 void UpdateDataProvider::RunInstallCallback(const std::string& extension_id,
                                             const base::FilePath& temp_dir) {
   if (!context_) {
     base::PostTaskWithTraits(
-        FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                       base::TaskPriority::BACKGROUND),
+        FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
         base::Bind(base::IgnoreResult(&base::DeleteFile), temp_dir, false));
     return;
   } else {
     callback_.Run(context_, extension_id, temp_dir);
   }
 }
 
 }  // namespace extensions