Minimize the delegate dependencies for non persistent notifications.

chrome/browser/notifications/persistent_notification_handler.h

Index: chrome/browser/notifications/persistent_notification_handler.h
diff --git a/chrome/browser/notifications/persistent_notification_handler.h b/chrome/browser/notifications/persistent_notification_handler.h
index 577f8ba45807c80a4d1ff1b883d60af968707a0b..5532097b9be8ba6c0a2f7ff5587bae5d945b956d 100644
--- a/chrome/browser/notifications/persistent_notification_handler.h
+++ b/chrome/browser/notifications/persistent_notification_handler.h
@@ -8,8 +8,6 @@
 #include "base/macros.h"
 #include "chrome/browser/notifications/notification_handler.h"
 
-class NotificationDelegate;
-
 // NotificationHandler implementation for persistent, service worker backed,
 // notifications.
 class PersistentNotificationHandler : public NotificationHandler {
@@ -28,8 +26,6 @@ class PersistentNotificationHandler : public NotificationHandler {
                int action_index,
                const base::NullableString16& reply) override;
   void OpenSettings(Profile* profile) override;
-  void RegisterNotification(const std::string& notification_id,
-                            NotificationDelegate* delegate) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PersistentNotificationHandler);