Use constexpr TaskTraits constructor in chrome.

chrome/browser/extensions/api/networking_private/networking_private_credentials_getter_browsertest.cc

 // Copyright 2017 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 "base/bind.h"
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/run_loop.h"
 #include "base/task_scheduler/post_task.h"
 #include "chrome/browser/extensions/api/networking_private/networking_private_credentials_getter.h"
@@ skipping 11 matching lines @@
 
   void RunTest(bool use_test_network) {
     base::RunLoop run_loop;
     quit_closure_ = run_loop.QuitClosure();
 
     if (use_test_network)
       network_ = extensions::mojom::WiFiCredentialsGetter::kWiFiTestNetwork;
 
     done_called_ = false;
     base::PostTaskWithTraits(
-        FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
-                       base::TaskPriority::BACKGROUND),
+        FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
         base::Bind(&NetworkingPrivateCredentialsGetterTest::GetCredentials,
                    base::Unretained(this)));
     run_loop.Run();
 
     EXPECT_TRUE(done_called_);
   }
 
  private:
   void GetCredentials() {
     std::unique_ptr<extensions::NetworkingPrivateCredentialsGetter> getter(
@@ skipping 28 matching lines @@
 
 IN_PROC_BROWSER_TEST_F(NetworkingPrivateCredentialsGetterTest,
                        GetCredentialsSuccess) {
   RunTest(true);
 }
 
 IN_PROC_BROWSER_TEST_F(NetworkingPrivateCredentialsGetterTest,
                        GetCredentialsFailure) {
   RunTest(false);
 }