Remove NoNotificationMessageView from empty message center

ui/message_center/views/message_center_button_bar.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_MESSAGE_CENTER_BUTTON_BAR_H_
 #define UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_BUTTON_BAR_H_
 
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "ui/message_center/message_center_export.h"
@@ skipping 21 matching lines @@
  public:
   MessageCenterButtonBar(MessageCenterView* message_center_view,
                          MessageCenter* message_center,
                          NotifierSettingsProvider* notifier_settings_provider,
                          bool settings_initially_visible,
                          const base::string16& title);
   ~MessageCenterButtonBar() override;
 
   // Enables or disables all of the buttons in the center.  This is used to
   // prevent user clicks during the close-all animation.
-  virtual void SetAllButtonsEnabled(bool enabled);
+  void SetSettingsAndQuietModeButtonsEnabled(bool enabled);
 
   // Sometimes we shouldn't see the close-all button.
   void SetCloseAllButtonEnabled(bool enabled);
 
   MESSAGE_CENTER_EXPORT views::Button* GetCloseAllButtonForTest() const;
 
   // Sometimes we shouldn't see the back arrow (not in settings).
   void SetBackArrowVisible(bool visible);
 
  private:
@@ skipping 31 matching lines @@
   NotificationCenterButton* close_all_button_;
   NotificationCenterButton* settings_button_;
   NotificationCenterButton* quiet_mode_button_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageCenterButtonBar);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_BUTTON_BAR_H_