Revert of Implement support for closing mac native notifications

chrome/browser/ui/cocoa/notifications/notification_service_delegate.mm

 // Copyright 2016 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.
 
 #import <AppKit/AppKit.h>
 
 #import "chrome/browser/ui/cocoa/notifications/notification_service_delegate.h"
 
 #include "base/mac/scoped_nsobject.h"
 #import "chrome/browser/ui/cocoa/notifications/alert_notification_service.h"
@@ skipping 42 matching lines @@
 }
 
 // NSUserNotification center delegate
 - (void)userNotificationCenter:(NSUserNotificationCenter*)center
        didActivateNotification:(NSUserNotification*)notification {
   NSDictionary* response =
       [NotificationResponseBuilder buildDictionary:notification];
   [[connection_ remoteObjectProxy] notificationClick:response];
 }
 
-// _NSUserNotificationCenterDelegatePrivate
-- (void)userNotificationCenter:(NSUserNotificationCenter*)center
-               didDismissAlert:(NSUserNotification*)notification {
-  NSDictionary* response =
-      [NotificationResponseBuilder buildDictionary:notification];
-  [[connection_ remoteObjectProxy] notificationClick:response];
-}
-
 @end