Use constexpr TaskTraits constructor in base.

base/test/scoped_task_scheduler.h

 // Copyright 2016 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.
 
 #ifndef BASE_TEST_SCOPED_TASK_SCHEDULER_H_
 #define BASE_TEST_SCOPED_TASK_SCHEDULER_H_
 
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 
@@ skipping 23 matching lines @@
 // base::PostTask(FROM_HERE, base::Bind(&A));
 // base::RunLoop::RunUntilIdle(); // Returns after running A.
 //
 // In this snippet, run_loop.Run() returns after running "B" and
 // "RunLoop::Quit".
 // base::RunLoop run_loop;
 // base::PostTask(FROM_HERE, base::Bind(&B));
 // base::PostTask(FROM_HERE, base::Bind(&RunLoop::Quit, &run_loop));
 // base::PostTask(FROM_HERE, base::Bind(&C));
 // base::PostTaskWithTraits(
-//     base::TaskTraits().WithShutdownBehavior(
-//         base::TaskShutdownBehavior::BLOCK_SHUTDOWN),
+//     {base::TaskShutdownBehavior::BLOCK_SHUTDOWN},
 //     base::Bind(&D));
 // run_loop.Run();  // Returns after running B and RunLoop::Quit.
 //
 // At this point, |scoped_task_scheduler| will be destroyed. The destructor
 // runs "D" because it's BLOCK_SHUTDOWN. "C" is skipped.
 class ScopedTaskScheduler {
  public:
   // Registers a synchronous TaskScheduler on a thread that doesn't have a
   // MessageLoop.
   //
@@ skipping 38 matching lines @@
   const TaskScheduler* task_scheduler_ = nullptr;
   ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedTaskScheduler);
 };
 
 }  // namespace test
 }  // namespace base
 
 #endif  // BASE_TEST_SCOPED_TASK_SCHEDULER_H_