Add TaskScheduler::JoinForTesting().

base/task_scheduler/scheduler_worker_pool_impl.cc

Index: base/task_scheduler/scheduler_worker_pool_impl.cc
diff --git a/base/task_scheduler/scheduler_worker_pool_impl.cc b/base/task_scheduler/scheduler_worker_pool_impl.cc
index 912d27015d21dc89d8c0bfc056bf9ee9cc988e03..eb8f02df84eb9ce4e7335984e90ed337b5a5e1d3 100644
--- a/base/task_scheduler/scheduler_worker_pool_impl.cc
+++ b/base/task_scheduler/scheduler_worker_pool_impl.cc
@@ -413,8 +413,6 @@ void SchedulerWorkerPoolImpl::WaitForAllWorkersIdleForTesting() {
 }
 
 void SchedulerWorkerPoolImpl::JoinForTesting() {
-  DCHECK(!CanWorkerDetachForTesting() || suggested_reclaim_time_.is_max())
-      << "Workers can detach during join.";
   for (const auto& worker : workers_)
     worker->JoinForTesting();
 
@@ -422,10 +420,6 @@ void SchedulerWorkerPoolImpl::JoinForTesting() {
   join_for_testing_returned_.Signal();
 }
 
-void SchedulerWorkerPoolImpl::DisallowWorkerDetachmentForTesting() {
-  worker_detachment_disallowed_.Set();
-}
-
 size_t SchedulerWorkerPoolImpl::NumberOfAliveWorkersForTesting() {
   size_t num_alive_workers = 0;
   for (const auto& worker : workers_) {
@@ -610,8 +604,7 @@ bool SchedulerWorkerPoolImpl::SchedulerWorkerDelegateImpl::CanDetach(
       !idle_start_time_.is_null() &&
       (TimeTicks::Now() - idle_start_time_) > outer_->suggested_reclaim_time_ &&
       worker != outer_->PeekAtIdleWorkersStack() &&
-      !subtle::NoBarrier_Load(&num_single_threaded_runners_) &&
-      outer_->CanWorkerDetachForTesting();
+      !subtle::NoBarrier_Load(&num_single_threaded_runners_);
   return can_detach;
 }
 
@@ -755,9 +748,5 @@ void SchedulerWorkerPoolImpl::RemoveFromIdleWorkersStack(
   idle_workers_stack_.Remove(worker);
 }
 
-bool SchedulerWorkerPoolImpl::CanWorkerDetachForTesting() {
-  return !worker_detachment_disallowed_.IsSet();
-}
-
 }  // namespace internal
 }  // namespace base