Add VectorIconButton functionality to ImageButton.

ui/views/examples/button_example.h

 // Copyright (c) 2012 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_VIEWS_EXAMPLES_BUTTON_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_BUTTON_EXAMPLE_H_
 
 #include "base/macros.h"
 #include "ui/views/controls/button/button.h"
+#include "ui/views/controls/button/image_button.h"
 #include "ui/views/examples/example_base.h"
 
 namespace views {
 
 class ImageButton;
 class LabelButton;
 class MdTextButton;
 
 namespace examples {
 
 // ButtonExample simply counts the number of clicks.
 class VIEWS_EXAMPLES_EXPORT ButtonExample : public ExampleBase,
-                                            public ButtonListener {
+                                            public ImageButtonDelegate {
  public:
   ButtonExample();
   ~ButtonExample() override;
 
   // ExampleBase:
   void CreateExampleView(View* container) override;
 
  private:
   void LabelButtonPressed(LabelButton* label_button, const ui::Event& event);
 
-  // ButtonListener:
+  // ImageButtonDelegate:
   void ButtonPressed(Button* sender, const ui::Event& event) override;
 
   // Example buttons.
   LabelButton* label_button_ = nullptr;
   LabelButton* styled_button_ = nullptr;
   LabelButton* disabled_button_ = nullptr;
   MdTextButton* md_button_ = nullptr;
   MdTextButton* md_default_button_ = nullptr;
   ImageButton* image_button_ = nullptr;
 
   const gfx::ImageSkia* icon_ = nullptr;
 
   // The number of times the buttons are pressed.
   int count_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(ButtonExample);
 };
 
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_BUTTON_EXAMPLE_H_