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

ash/devtools/ui_element_delegate.h

Index: ash/devtools/ui_element_delegate.h
diff --git a/ash/devtools/ui_element_delegate.h b/ash/devtools/ui_element_delegate.h
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+++ b/ash/devtools/ui_element_delegate.h
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+// 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_