Revert of Improves focus/activation for aura-mus and DesktopNativeWidgetAura

ui/aura/mus/focus_synchronizer_delegate.h

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef UI_AURA_MUS_FOCUS_SYNCHRONIZER_DELEGATE_H_
-#define UI_AURA_MUS_FOCUS_SYNCHRONIZER_DELEGATE_H_
-
-#include <stdint.h>
-
-#include "ui/aura/aura_export.h"
-
-namespace aura {
-
-class WindowMus;
-
-// Used by FocusSynchronizer to create a change id when focus changes. The
-// change id is then sent to ui::mojom::WindowTree.
-class AURA_EXPORT FocusSynchronizerDelegate {
- public:
-  virtual uint32_t CreateChangeIdForFocus(WindowMus* window) = 0;
-
- protected:
-  virtual ~FocusSynchronizerDelegate() {}
-};
-
-}  // namespace aura
-
-#endif  // UI_AURA_MUS_FOCUS_SYNCHRONIZER_DELEGATE_H_