Revert of ash: Use system tray mojo interface to show system update tray icon

ash/common/system/tray/system_tray_controller.cc

Index: ash/common/system/tray/system_tray_controller.cc
diff --git a/ash/common/system/tray/system_tray_controller.cc b/ash/common/system/tray/system_tray_controller.cc
index e4e8db7a03cc3969fcd39cb35f52332df9297ae4..659cd531d79de85487ef187c8ceb0328dc34f3dd 100644
--- a/ash/common/system/tray/system_tray_controller.cc
+++ b/ash/common/system/tray/system_tray_controller.cc
@@ -4,12 +4,8 @@
 
 #include "ash/common/system/tray/system_tray_controller.h"
 
-#include "ash/common/system/tray/system_tray.h"
 #include "ash/common/system/tray/system_tray_notifier.h"
-#include "ash/common/system/update/tray_update.h"
-#include "ash/common/wm_root_window_controller.h"
 #include "ash/common/wm_shell.h"
-#include "ash/common/wm_window.h"
 
 namespace ash {
 
@@ -132,16 +128,4 @@
   WmShell::Get()->system_tray_notifier()->NotifyDateFormatChanged();
 }
 
-void SystemTrayController::ShowUpdateIcon(mojom::UpdateSeverity severity,
-                                          bool factory_reset_required) {
-  // Show the icon on all displays.
-  for (WmWindow* root : WmShell::Get()->GetAllRootWindows()) {
-    ash::SystemTray* tray = root->GetRootWindowController()->GetSystemTray();
-    // External monitors might not have a tray yet.
-    if (!tray)
-      continue;
-    tray->tray_update()->ShowUpdateIcon(severity, factory_reset_required);
-  }
-}
-
 }  // namespace ash