Adjust behavior of control buttons of notifications.

ui/message_center/views/padded_button.h

 // Copyright 2013 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_MESSAGE_CENTER_VIEWS_PADDED_BUTTON_H_
 #define UI_MESSAGE_CENTER_VIEWS_PADDED_BUTTON_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ui/message_center/message_center_export.h"
+#include "ui/views/animation/ink_drop.h"
+#include "ui/views/animation/ink_drop_ripple.h"
 #include "ui/views/controls/button/image_button.h"
 
 namespace message_center {
 
 // PaddedButtons are ImageButtons whose image can be padded within the button.
 // This allows the creation of buttons like the notification close and expand
 // buttons whose clickable areas extends beyond their image areas
 // (<http://crbug.com/168822>) without the need to create and maintain
 // corresponding resource images with alpha padding. In the future, this class
 // will also allow for buttons whose touch areas extend beyond their clickable
 // area (<http://crbug.com/168856>).
 class MESSAGE_CENTER_EXPORT PaddedButton : public views::ImageButton {
  public:
   PaddedButton(views::ButtonListener* listener);
-  ~PaddedButton() override;
+  ~PaddedButton() override = default;
+
+  // Overridden from InkDropHostView
+  std::unique_ptr<views::InkDrop> CreateInkDrop() override;
+  std::unique_ptr<views::InkDropRipple> CreateInkDropRipple() const override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PaddedButton);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_PADDED_BUTTON_H_