chromeos: Move device shutdown handling out of chrome into ash

ash/test/lock_state_controller_test_api.cc

Index: ash/test/lock_state_controller_test_api.cc
diff --git a/ash/test/lock_state_controller_test_api.cc b/ash/test/lock_state_controller_test_api.cc
index b1734685e5bcc089e12298daf4dc38bf2ce423fa..bab5468d1f0cd069511f6ab5fdd3d9390341ffbc 100644
--- a/ash/test/lock_state_controller_test_api.cc
+++ b/ash/test/lock_state_controller_test_api.cc
@@ -20,10 +20,5 @@ LockStateControllerTestApi::LockStateControllerTestApi(
 
 LockStateControllerTestApi::~LockStateControllerTestApi() {}
 
-void LockStateControllerTestApi::SetShutdownClient(
-    std::unique_ptr<mojom::ShutdownClient> client) {
-  controller_->shutdown_client_ = std::move(client);
-}
-
 }  // namespace test
 }  // namespace ash