Show the settings button on a pinned 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/message_center/views/padded_button.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 Widget;
 }
 
 namespace arc {
 
 class ArcCustomNotificationView
     : public views::NativeViewHost,
       public views::ButtonListener,
       public aura::WindowObserver,
       public ArcCustomNotificationItem::Observer,
       public ArcNotificationSurfaceManager::Observer {
  public:
   explicit ArcCustomNotificationView(ArcCustomNotificationItem* item);
   ~ArcCustomNotificationView() override;
 
   std::unique_ptr<message_center::CustomNotificationContentViewDelegate>
   CreateContentViewDelegate();
 
  private:
   class ContentViewDelegate;
-  class ControlButton;
   class EventForwarder;
   class SettingsButton;
   class SlideHelper;
 
+  // A image button class used for the settings button and the close button.
+  // We can't use forward declaration for this class due to std::unique_ptr<>
+  // requires size of this class.
+  class ControlButton : public message_center::PaddedButton {
+   public:
+    explicit ControlButton(ArcCustomNotificationView* owner);
+    void OnFocus() override;
+    void OnBlur() override;
+
+   private:
+    ArcCustomNotificationView* const owner_;
+
+    DISALLOW_COPY_AND_ASSIGN(ControlButton);
+  };
+
+  void CreateCloseButton();
   void CreateFloatingControlButtons();
   void SetSurface(exo::NotificationSurface* surface);
   void UpdatePreferredSize();
   void UpdateControlButtonsVisibility();
   void UpdatePinnedState();
   void UpdateSnapshot();
   void AttachSurface();
   void ActivateToast();
 
   // views::NativeViewHost
@@ skipping 42 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;
-  ControlButton* close_button_ = nullptr;
+  std::unique_ptr<ControlButton> close_button_;
   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_