mash: Run pre-unlock animation via SessionController

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 77886786a586272002929abdbd85b74d426eaa2c..0b656e29272e3a118423c2d9f29aa9dca0b48904 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -272,10 +272,6 @@ class ASH_EXPORT Shell : public SessionStateObserver,
   // Called when the application is exiting.
   void OnAppTerminating();
 
-  // Called when the screen is locked (after the lock window is visible) or
-  // unlocked.
-  void OnLockStateChanged(bool locked);
-
   // Called when a casting session is started or stopped.
   void OnCastingSessionStartedOrStopped(bool started);
 
@@ -638,6 +634,7 @@ class ASH_EXPORT Shell : public SessionStateObserver,
   // SessionStateObserver:
   void SessionStateChanged(session_manager::SessionState state) override;
   void LoginStatusChanged(LoginStatus login_status) override;
+  void LockStateChanged(bool locked) override;
 
   // Callback for prefs::ConnectToPrefService.
   void OnPrefServiceInitialized(std::unique_ptr<::PrefService> pref_service);