Add TaskScheduler::JoinForTesting().

base/task_scheduler/task_scheduler_impl.cc

 // 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.
 
 #include "base/task_scheduler/task_scheduler_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 76 matching lines @@
 void TaskSchedulerImpl::FlushForTesting() {
   DCHECK(task_tracker_);
   task_tracker_->Flush();
 }
 
 void TaskSchedulerImpl::JoinForTesting() {
 #if DCHECK_IS_ON()
   DCHECK(!join_for_testing_returned_.IsSet());
 #endif
   for (const auto& worker_pool : worker_pools_)
+    worker_pool->DisallowWorkerDetachmentForTesting();
+  for (const auto& worker_pool : worker_pools_)
     worker_pool->JoinForTesting();
   service_thread_.Stop();
 #if DCHECK_IS_ON()
   join_for_testing_returned_.Set();
 #endif
 }
 
 TaskSchedulerImpl::TaskSchedulerImpl(const WorkerPoolIndexForTraitsCallback&
                                          worker_pool_index_for_traits_callback)
     : service_thread_("TaskSchedulerServiceThread"),
@@ skipping 70 matching lines @@
   // in |sequence|.
   const TaskTraits traits =
       sequence->PeekTaskTraits().WithPriority(sort_key.priority());
 
   GetWorkerPoolForTraits(traits)->ReEnqueueSequence(std::move(sequence),
                                                     sort_key);
 }
 
 }  // namespace internal
 }  // namespace base