mash: Port TrayUpdateTest to AshTest

ash/common/system/update/tray_update_unittest.cc

Index: ash/common/system/update/tray_update_unittest.cc
diff --git a/ash/common/system/update/tray_update_unittest.cc b/ash/common/system/update/tray_update_unittest.cc
index 71abb8705773c743fa0a1da253c9ca8ab17fff9b..1c6c796dbfaa3752e9b15abfa97b42957a32b0de 100644
--- a/ash/common/system/update/tray_update_unittest.cc
+++ b/ash/common/system/update/tray_update_unittest.cc
@@ -5,15 +5,14 @@
 #include "ash/common/system/update/tray_update.h"
 
 #include "ash/common/system/tray/system_tray.h"
+#include "ash/common/system/tray/system_tray_delegate.h"
 #include "ash/common/system/tray/system_tray_notifier.h"
-#include "ash/common/test/test_system_tray_delegate.h"
+#include "ash/common/test/ash_test.h"
 #include "ash/common/wm_shell.h"
-#include "ash/test/ash_test_base.h"
-#include "base/macros.h"
 
 namespace ash {
 
-using TrayUpdateTest = test::AshTestBase;
+using TrayUpdateTest = AshTest;
 
 // Tests that the update icon becomes visible when an update becomes
 // available.
@@ -21,9 +20,8 @@ TEST_F(TrayUpdateTest, VisibilityAfterUpdate) {
   TrayUpdate* tray_update = GetPrimarySystemTray()->GetTrayUpdateForTesting();
 
   // The system starts with no update pending.
-  test::TestSystemTrayDelegate* tray_delegate = GetSystemTrayDelegate();
   UpdateInfo initial_info;
-  tray_delegate->GetSystemUpdateInfo(&initial_info);
+  WmShell::Get()->system_tray_delegate()->GetSystemUpdateInfo(&initial_info);
   EXPECT_FALSE(initial_info.update_required);
 
   // When no update is pending, the item isn't visible.