Show no-notification message in the bottom label of 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 26 matching lines @@
 // center.
 class MESSAGE_CENTER_EXPORT MessageCenterView : public views::View,
                                                 public MessageCenterObserver,
                                                 public MessageCenterController,
                                                 public gfx::AnimationDelegate {
  public:
   MessageCenterView(MessageCenter* message_center,
                     MessageCenterTray* tray,
                     int max_height,
                     bool initially_settings_visible,
-                    bool top_down,
-                    const base::string16& title);
+                    bool top_down);
   ~MessageCenterView() override;
 
   void SetNotifications(const NotificationList::Notifications& notifications);
 
   void ClearAllClosableNotifications();
   void OnAllNotificationsCleared();
 
   size_t NumMessageViewsForTest() const;
 
   void SetSettingsVisible(bool visible);
@@ skipping 31 matching lines @@
   // 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;
 
   void AddNotificationAt(const Notification& notification, int index);
   void NotificationsChanged();
+  base::string16 GetButtonBarTitle() const;
   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.
 
@@ skipping 24 matching lines @@
   bool is_closing_;
 
   std::unique_ptr<MessageViewContextMenuController> context_menu_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageCenterView);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_VIEW_H_