Flush TaskScheduler in ~ScopedTaskEnvironment and ~ScopedAsyncTaskScheduler.

base/test/scoped_task_environment.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/test/scoped_task_environment.h"
 
 #include "base/run_loop.h"
 #include "base/task_scheduler/scheduler_worker_pool_params.h"
 #include "base/task_scheduler/task_scheduler.h"
 #include "base/time/time.h"
@@ skipping 14 matching lines @@
   TaskScheduler::CreateAndSetDefaultTaskScheduler(
       "ScopedTaskEnvironment", {worker_pool_params, worker_pool_params,
                                 worker_pool_params, worker_pool_params});
   task_scheduler_ = TaskScheduler::GetInstance();
 }
 
 ScopedTaskEnvironment::~ScopedTaskEnvironment() {
   RunLoop().RunUntilIdle();
 
   DCHECK_EQ(TaskScheduler::GetInstance(), task_scheduler_);
+  TaskScheduler::GetInstance()->FlushForTesting();

[gab, 2017/04/12 19:18:34]

Add a comment explaining why it's required.

[fdoray, 2017/04/12 19:38:05]

Done.

   TaskScheduler::GetInstance()->Shutdown();
   TaskScheduler::GetInstance()->JoinForTesting();
   TaskScheduler::SetInstance(nullptr);
 }
 
 }  // namespace test
 }  // namespace base