mash: Shell ref clean up for screen lock

ash/session/session_controller.cc

Index: ash/session/session_controller.cc
diff --git a/ash/session/session_controller.cc b/ash/session/session_controller.cc
index 94ee2bfb5c95e8490c8383bda63fd203821425c1..26a0752d027344684643ee4fa5412eeb7024841a 100644
--- a/ash/session/session_controller.cc
+++ b/ash/session/session_controller.cc
@@ -8,6 +8,7 @@
 
 #include "ash/session/session_observer.h"
 #include "ash/shell.h"
+#include "ash/system/power/power_event_observer.h"
 #include "ash/wm/lock_state_controller.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ -246,6 +247,10 @@ void SessionController::StartLock(const StartLockCallback& callback) {
   lock_state_controller->OnStartingLock();
 }
 
+void SessionController::NotifyChromeLockAnimationsComplete() {
+  Shell::Get()->power_event_observer()->OnLockAnimationsComplete();
+}
+
 void SessionController::RunUnlockAnimation(
     const RunUnlockAnimationCallback& callback) {
   is_unlocking_ = true;