Remove NoNotificationMessageView from empty message center

ui/message_center/views/message_center_view.h

 // Copyright (c) 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_MESSAGE_CENTER_VIEW_H_
 #define UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_VIEW_H_
 
 #include <stddef.h>
 
 #include "base/macros.h"
@@ skipping 77 matching lines @@
   void ClickOnSettingsButton(const std::string& notification_id) override;
 
   // Overridden from gfx::AnimationDelegate:
   void AnimationEnded(const gfx::Animation* animation) override;
   void AnimationProgressed(const gfx::Animation* animation) override;
   void AnimationCanceled(const gfx::Animation* animation) override;
 
  private:
   friend class MessageCenterViewTest;
 
+  enum class Mode { NOTIFICATIONS, SETTINGS, BUTTONS_ONLY };
+
   void AddNotificationAt(const Notification& notification, int index);
-  void NotificationsChanged();
+  void Update(bool animate);
+  void SetVisibilityMode(Mode mode, bool animate);
+  void UpdateButtonsStatus();
   void SetNotificationViewForTest(MessageView* view);
 
   MessageCenter* message_center_;  // Weak reference.
   MessageCenterTray* tray_;  // Weak reference.
 
   // Map notification_id->NotificationView*. It contains all NotificationViews
   // currently displayed in MessageCenter.
   typedef std::map<std::string, NotificationView*> NotificationViewsMap;
   NotificationViewsMap notification_views_;  // Weak.
 
   // Child views.
   views::ScrollView* scroller_;
   std::unique_ptr<MessageListView> message_list_view_;
-  std::unique_ptr<views::View> empty_list_view_;
   NotifierSettingsView* settings_view_;
   MessageCenterButtonBar* button_bar_;
   bool top_down_;
 
   // Data for transition animation between settings view and message list.
   bool settings_visible_;
 
   // Animation managing transition between message center and settings (and vice
   // versa).
   std::unique_ptr<gfx::MultiAnimation> settings_transition_animation_;
 
   // Helper data to keep track of the transition between settings and
   // message center views.
   views::View* source_view_;
   int source_height_;
   views::View* target_view_;
   int target_height_;
 
   // True when the widget is closing so that further operations should be
   // ignored.
   bool is_closing_;
 
+  bool is_clearing_ = false;
+
+  // Current view mode. During animation, it is the target mode.
+  Mode mode_ = Mode::BUTTONS_ONLY;
+
   std::unique_ptr<MessageViewContextMenuController> context_menu_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageCenterView);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_VIEW_H_