Remove the old signature of NotificationManager::closePersistent().

The origin now is included, and Blink has been updated to pass it in.

This is part of a three-sided patch:
  [1] https://codereview.chromium.org/982313002/
  [2] https://codereview.chromium.org/985063002/
  [3] This patch.

BUG=447628

Review URL: https://codereview.chromium.org/985693004

Cr-Commit-Position: refs/heads/master@{#320928}

content/child/notifications/notification_manager.cc

@@ -141,11 +141,6 @@ void NotificationManager::closePersistent(
       base::UTF16ToUTF8(persistent_notification_id)));
 }
 
-void NotificationManager::closePersistent(
-    const blink::WebString& persistent_notification_id) {
-  closePersistent(blink::WebSerializedOrigin(), persistent_notification_id);
-}
-
 void NotificationManager::notifyDelegateDestroyed(
     blink::WebNotificationDelegate* delegate) {
   if (pending_notifications_.CancelPageNotificationFetches(delegate))

content/child/notifications/notification_manager.h

@@ -49,9 +49,6 @@ class NotificationManager : public blink::WebNotificationManager,
   virtual void closePersistent(
       const blink::WebSerializedOrigin& origin,
       const blink::WebString& persistent_notification_id);
-  // TODO(peter): Remove this method when Blink has been updated.
-  virtual void closePersistent(
-      const blink::WebString& persistent_notification_id);
   virtual void notifyDelegateDestroyed(
       blink::WebNotificationDelegate* delegate);
   virtual blink::WebNotificationPermission checkPermission(