Adjust behavior of control buttons of notifications.

ui/message_center/views/notification_view.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_MESSAGE_CENTER_VIEWS_NOTIFICATION_VIEW_H_
 #define UI_MESSAGE_CENTER_VIEWS_NOTIFICATION_VIEW_H_
 
 #include <vector>
 
 #include "base/gtest_prod_util.h"
@@ skipping 28 matching lines @@
                    const Notification& notification);
   ~NotificationView() override;
 
   // Overridden from views::View:
   gfx::Size GetPreferredSize() const override;
   int GetHeightForWidth(int width) const override;
   void Layout() override;
   void OnFocus() override;
   void ScrollRectToVisible(const gfx::Rect& rect) override;
   gfx::NativeCursor GetCursor(const ui::MouseEvent& event) override;
+  void OnMouseEntered(const ui::MouseEvent& event) override;
+  void OnMouseExited(const ui::MouseEvent& event) override;
 
   // Overridden from MessageView:
   void UpdateWithNotification(const Notification& notification) override;
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
   bool IsCloseButtonFocused() const override;
   void RequestFocusOnCloseButton() override;
   bool IsPinned() const override;
+  void UpdateControlButtonsVisibility() override;
 
  protected:
   views::ImageButton* close_button() { return close_button_.get(); }
 
  private:
   FRIEND_TEST_ALL_PREFIXES(NotificationViewTest, CreateOrUpdateTest);
   FRIEND_TEST_ALL_PREFIXES(NotificationViewTest,
                            CreateOrUpdateTestSettingsButton);
   FRIEND_TEST_ALL_PREFIXES(NotificationViewTest, FormatContextMessageTest);
   FRIEND_TEST_ALL_PREFIXES(NotificationViewTest, SettingsButtonTest);
@@ skipping 50 matching lines @@
   std::vector<views::View*> separators_;
   std::unique_ptr<views::ImageButton> close_button_ = nullptr;
   std::unique_ptr<views::ImageView> small_image_view_;
 
   DISALLOW_COPY_AND_ASSIGN(NotificationView);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_NOTIFICATION_VIEW_H_