Abstract notification clicks in its own dictionary

chrome/browser/ui/cocoa/notifications/notification_builder_mac.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_NOTIFICATIONS_NOTIFICATION_BUILDER_MAC_H_
 #define CHROME_BROWSER_UI_COCOA_NOTIFICATIONS_NOTIFICATION_BUILDER_MAC_H_
 
 #import <Foundation/Foundation.h>
 
 #include "base/mac/scoped_nsobject.h"
 
 @class NSUserNotification;
 
-namespace notification_builder {
-
-extern NSString* const kNotificationOrigin;
-extern NSString* const kNotificationId;
-extern NSString* const kNotificationProfileId;
-extern NSString* const kNotificationIncognito;
-
-}  // notification_builder
-
 // Provides a marshallable way for storing the information required to construct
 // a NSUSerNotification that is to be displayed on the system.
 //
 // A quick example:
 //     base::scoped_nsobject<NotificationBuilder> builder(
 //         [[NotificationBuilder alloc] init]);
 //     [builder setTitle:@"Hello"];
 //
 //     // Build a notification out of the data.
 //     NSUserNotification* notification =
@@ skipping 36 matching lines @@
 - (NSUserNotification*)buildUserNotification;
 
 // Returns a representation of a notification that can be serialized.
 // Another instance of NotificationBuilder can read this directly and generate
 // a notification out of it via the |buildbuildUserNotification| method.
 - (NSDictionary*)buildDictionary;
 
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_NOTIFICATIONS_NOTIFICATION_BUILDER_MAC_H_