Add an empty message to the notification center.

ui/message_center/cocoa/tray_view_controller.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_COCOA_TRAY_VIEW_CONTROLLER_H_
 #define UI_MESSAGE_CENTER_COCOA_TRAY_VIEW_CONTROLLER_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include <list>
@@ skipping 28 matching lines @@
  @private
   // Controller of the notifications, where action messages are forwarded. Weak.
   message_center::MessageCenter* messageCenter_;
 
   // The back button shown while the settings are open.
   base::scoped_nsobject<HoverImageButton> backButton_;
 
   // The "Notifications" label at the top.
   base::scoped_nsobject<NSTextField> title_;
 
+  // The 1px horizontal divider between the scroll view and the title bar.
+  base::scoped_nsobject<NSBox> divider_;
+
+  // The "Nothing to see here" label in an empty message center.
+  base::scoped_nsobject<NSTextField> emptyDescription_;
+
   // The scroll view that contains all the notifications in its documentView.
   base::scoped_nsobject<NSScrollView> scrollView_;
 
   // The clip view that manages how scrollView_'s documentView is clipped.
   base::scoped_nsobject<MCClipView> clipView_;
 
   // Array of MCNotificationController objects, which the array owns.
   base::scoped_nsobject<NSMutableArray> notifications_;
 
   // Map of notification IDs to weak pointers of the view controllers in
@@ skipping 91 matching lines @@
 + (CGFloat)maxTrayClientHeight;
 
 // Returns the width of the notifications tray.
 + (CGFloat)trayWidth;
 
 @end
 
 // Testing API /////////////////////////////////////////////////////////////////
 
 @interface MCTrayViewController (TestingAPI)
+- (NSBox*)divider;
+- (NSTextField*)emptyDescription;
 - (NSScrollView*)scrollView;
 - (HoverImageButton*)pauseButton;
 - (HoverImageButton*)clearAllButton;
 
 // Setter for changing the animation duration. The testing code could set it
 // to a very small value to expedite the test running.
 - (void)setAnimationDuration:(NSTimeInterval)duration;
 
 // Setter for changing the clear-all animation delay. The testing code could set
 // it to a very small value to expedite the test running.
 - (void)setAnimateClearingNextNotificationDelay:(NSTimeInterval)delay;
 
 // Setter for testingAnimationEndedCallback_. The testing code could set it
 // to get called back when the animation ends.
 - (void)setAnimationEndedCallback:
     (message_center::TrayAnimationEndedCallback)callback;
 @end
 
 #endif  // UI_MESSAGE_CENTER_COCOA_TRAY_VIEW_CONTROLLER_H_