Add VectorIconButton functionality to ImageButton.

ash/common/system/date/date_default_view.h

 // Copyright 2014 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_COMMON_SYSTEM_DATE_DATE_DEFAULT_VIEW_H_
 #define ASH_COMMON_SYSTEM_DATE_DATE_DEFAULT_VIEW_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/login_status.h"
 #include "base/macros.h"
-#include "ui/views/controls/button/button.h"
+#include "ui/views/controls/button/image_button.h"
 #include "ui/views/view.h"
 
 namespace ash {
 namespace tray {
 class DateView;
 }  // namespace tray
 
 class SystemTrayItem;
 class TrayPopupHeaderButton;
 
 // The system tray bubble view with the date and buttons for help, lock and
 // shutdown.
 // TODO(tdanderson): Remove this class once material design is enabled by
 // default. See crbug.com/614453.
 class ASH_EXPORT DateDefaultView : public views::View,
-                                   public views::ButtonListener {
+                                   public views::ImageButtonDelegate {
  public:
   DateDefaultView(SystemTrayItem* owner, LoginStatus login);
 
   ~DateDefaultView() override;
 
   views::View* GetHelpButtonView();
   const views::View* GetShutdownButtonViewForTest() const;
 
   tray::DateView* GetDateView();
   const tray::DateView* GetDateView() const;
 
  private:
-  // Overridden from views::ButtonListener.
+  // views::ImageButtonDelegate:
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
   TrayPopupHeaderButton* help_button_;
   TrayPopupHeaderButton* shutdown_button_;
   TrayPopupHeaderButton* lock_button_;
   tray::DateView* date_view_;
 
   DISALLOW_COPY_AND_ASSIGN(DateDefaultView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_DATE_DATE_DEFAULT_VIEW_H_