Remove ink drop effect after clicking the settings button on an ARC notification.

ui/arc/notification/arc_custom_notification_view.h

 // Copyright 2016 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_ARC_NOTIFICATION_ARC_CUSTOM_NOTIFICATION_VIEW_H_
 #define UI_ARC_NOTIFICATION_ARC_CUSTOM_NOTIFICATION_VIEW_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "ui/arc/notification/arc_custom_notification_item.h"
 #include "ui/arc/notification/arc_notification_surface_manager.h"
 #include "ui/aura/window_observer.h"
 #include "ui/message_center/views/custom_notification_content_view_delegate.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/controls/native/native_view_host.h"
 
 namespace exo {
 class NotificationSurface;
 }
 
 namespace views {
 class FocusTraversable;
-class ImageButton;
 class Widget;
 }
 
 namespace arc {
 
 class ArcCustomNotificationView
     : public views::NativeViewHost,
       public views::ButtonListener,
       public aura::WindowObserver,
       public ArcCustomNotificationItem::Observer,
@@ skipping 67 matching lines @@
   // when a slide is in progress and restore the surface when it finishes.
   std::unique_ptr<SlideHelper> slide_helper_;
 
   // A control buttons on top of NotificationSurface. Needed because the
   // aura::Window of NotificationSurface is added after hosting widget's
   // RootView thus standard notification control buttons are always below
   // it.
   std::unique_ptr<views::Widget> floating_control_buttons_widget_;
 
   views::View* control_buttons_view_ = nullptr;
-  views::ImageButton* close_button_ = nullptr;
-  views::ImageButton* settings_button_ = nullptr;
+  ControlButton* close_button_ = nullptr;
+  ControlButton* settings_button_ = nullptr;
 
   // Protects from call loops between Layout and OnWindowBoundsChanged.
   bool in_layout_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(ArcCustomNotificationView);
 };
 
 }  // namespace arc
 
 #endif  // UI_ARC_NOTIFICATION_ARC_CUSTOM_NOTIFICATION_VIEW_H_