Revert of Create a unified UIElement interface for Widget, View and Window.

ash/devtools/ui_element_delegate.h

-// Copyright 2017 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 ASH_DEVTOOLS_UI_ELEMENT_DELEGATE_H_
-#define ASH_DEVTOOLS_UI_ELEMENT_DELEGATE_H_
-
-#include <vector>
-
-#include "ash/ash_export.h"
-#include "base/macros.h"
-#include "ui/aura/window.h"
-
-namespace ash {
-namespace devtools {
-
-class UIElement;
-
-class ASH_EXPORT UIElementDelegate {
- public:
-  UIElementDelegate(){};
-  virtual ~UIElementDelegate(){};
-
-  virtual void OnUIElementAdded(UIElement* parent, UIElement* child) = 0;
-
-  // Move |child| to different sibling index under |parent| in DOM tree.
-  virtual void OnUIElementReordered(UIElement* parent, UIElement* child) = 0;
-
-  // Remove ui_element in DOM tree.
-  virtual void OnUIElementRemoved(UIElement* ui_element) = 0;
-
-  // Update CSS agent when bounds change.
-  virtual void OnUIElementBoundsChanged(UIElement* ui_element) = 0;
-
-  // Return |window| highlighting status.
-  virtual bool IsHighlightingWindow(aura::Window* window) = 0;
-
-  DISALLOW_COPY_AND_ASSIGN(UIElementDelegate);
-};
-
-}  // namespace devtools
-}  // namespace ash
-
-#endif  // ASH_DEVTOOLS_UI_ELEMENT_DELEGATE_H_