Remove non-MD code from screen_tray_item.cc

ash/common/system/chromeos/screen_security/screen_tray_item.h

Index: ash/common/system/chromeos/screen_security/screen_tray_item.h
diff --git a/ash/common/system/chromeos/screen_security/screen_tray_item.h b/ash/common/system/chromeos/screen_security/screen_tray_item.h
index 5ed992a3d78f4f76305f2aa65ab471954cc430f8..eb4619d3e98c62636a1dcee887cba4ab3da184d8 100644
--- a/ash/common/system/chromeos/screen_security/screen_tray_item.h
+++ b/ash/common/system/chromeos/screen_security/screen_tray_item.h
@@ -7,21 +7,20 @@
 
 #include <string>
 
-#include "ash/common/system/tray/system_tray.h"
 #include "ash/common/system/tray/system_tray_item.h"
 #include "ash/common/system/tray/tray_item_view.h"
-#include "ash/common/system/tray/tray_notification_view.h"
 #include "base/macros.h"
 #include "ui/message_center/notification_delegate.h"
 #include "ui/views/controls/button/button.h"
-#include "ui/views/controls/image_view.h"
+#include "ui/views/view.h"
 
 namespace views {
-class View;
+class ImageView;
 }
 
 namespace ash {
 class ScreenTrayItem;
+class SystemTray;
 
 namespace tray {