Tests: Simplify SequencedWorkerPoolOwner, call Shutdown on destructor.

base/test/launcher/test_launcher.cc

Index: base/test/launcher/test_launcher.cc
diff --git a/base/test/launcher/test_launcher.cc b/base/test/launcher/test_launcher.cc
index e4b5bdaacecc25d2ef85a6e489e659480a62dae6..45b7111b45541363f9a4538164d09d3d3b59916a 100644
--- a/base/test/launcher/test_launcher.cc
+++ b/base/test/launcher/test_launcher.cc
@@ -467,10 +467,7 @@ TestLauncher::TestLauncher(TestLauncherDelegate* launcher_delegate,
       parallel_jobs_(parallel_jobs) {
 }
 
-TestLauncher::~TestLauncher() {
-  if (worker_pool_owner_)
-    worker_pool_owner_->pool()->Shutdown();
-}
+TestLauncher::~TestLauncher() {}
 
 bool TestLauncher::Run() {
   if (!Init())