[BackgroundSyncManager] Remove dead code

content/browser/background_sync/background_sync_manager.h

 // Copyright 2015 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 CONTENT_BROWSER_BACKGROUND_SYNC_BACKGROUND_SYNC_MANAGER_H_
 #define CONTENT_BROWSER_BACKGROUND_SYNC_BACKGROUND_SYNC_MANAGER_H_
 
 #include <list>
 #include <map>
 
@@ skipping 155 matching lines @@
   // null.
   bool LookupRegistration(int64 sw_registration_id,
                           const std::string& sync_registration_name,
                           BackgroundSyncRegistration* existing_registration);
 
   // Store all registrations for a given |sw_registration_id|.
   void StoreRegistrations(const GURL& origin,
                           int64 sw_registration_id,
                           const ServiceWorkerStorage::StatusCallback& callback);
 
-  // If the registration is in the map, removes it and returns the removed
-  // registration in |old_registration|. |old_registration| may be null.
+  // Removes the registration if it is in the map.
   void RemoveRegistrationFromMap(int64 sw_registration_id,
-                                 const std::string& sync_registration_name,
-                                 BackgroundSyncRegistration* old_registration);
+                                 const std::string& sync_registration_name);
 
   void AddRegistrationToMap(
       int64 sw_registration_id,
       const BackgroundSyncRegistration& sync_registration);
 
   void InitImpl(const base::Closure& callback);
   void InitDidGetDataFromBackend(
       const base::Closure& callback,
       const std::vector<std::pair<int64, std::string>>& user_data,
       ServiceWorkerStatusCode status);
@@ skipping 10 matching lines @@
 
   // Unregister callbacks
   void UnregisterImpl(
       const GURL& origin,
       int64 sw_registration_id,
       const std::string& sync_registration_name,
       BackgroundSyncRegistration::RegistrationId sync_registration_id,
       const StatusCallback& callback);
   void UnregisterDidStore(
       int64 sw_registration_id,
-      const BackgroundSyncRegistration& old_sync_registration,
       const StatusCallback& callback,
       ServiceWorkerStatusCode status);
 
   // GetRegistration callbacks
   void GetRegistrationImpl(const GURL& origin,
                            int64 sw_registration_id,
                            const std::string sync_registration_name,
                            const StatusAndRegistrationCallback& callback);
 
   // OnRegistrationDeleted callbacks
@@ skipping 23 matching lines @@
   bool disabled_;
 
   base::WeakPtrFactory<BackgroundSyncManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BackgroundSyncManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_BACKGROUND_SYNC_BACKGROUND_SYNC_MANAGER_H_