Revert of Tests: Simplify SequencedWorkerPoolOwner, call Shutdown on destructor.

base/threading/sequenced_task_runner_handle_unittest.cc

Index: base/threading/sequenced_task_runner_handle_unittest.cc
diff --git a/base/threading/sequenced_task_runner_handle_unittest.cc b/base/threading/sequenced_task_runner_handle_unittest.cc
index bd380efb68b0dbc6c39429eb903aef5f412b054d..1080262f32f1a8617f4fa2da7de3f0aa1f2d76fd 100644
--- a/base/threading/sequenced_task_runner_handle_unittest.cc
+++ b/base/threading/sequenced_task_runner_handle_unittest.cc
@@ -61,6 +61,7 @@
       base::Bind(&SequencedTaskRunnerHandleTest::GetTaskRunner,
                  base::Bind(&WaitableEvent::Signal, base::Unretained(&event))));
   event.Wait();
+  owner.pool()->Shutdown();
 }
 
 class ThreadRunner : public DelegateSimpleThread::Delegate {