[BackgroundSync] Clean up some style nits and unnecessary checks

content/child/background_sync/background_sync_provider.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_CHILD_BACKGROUND_SYNC_BACKGROUND_SYNC_PROVIDER_H_
 #define CONTENT_CHILD_BACKGROUND_SYNC_BACKGROUND_SYNC_PROVIDER_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 16 matching lines @@
 
   ~BackgroundSyncProvider() override;
 
   // blink::WebSyncProvider implementation
   // TODO(jkarlin) convert int64_t handle_id to int handle_id in all
   // WebSyncProvider functions.
   void registerBackgroundSync(
       const blink::WebSyncRegistration* options,
       blink::WebServiceWorkerRegistration* service_worker_registration,
       bool requested_from_service_worker,
-      blink::WebSyncRegistrationCallbacks* callbacks);
+      blink::WebSyncRegistrationCallbacks* callbacks) override;
   // TODO(jkarlin) remove |tag| parameter.
   void unregisterBackgroundSync(
       blink::WebSyncRegistration::Periodicity periodicity,
       int64_t handle_id,
       const blink::WebString& tag,
       blink::WebServiceWorkerRegistration* service_worker_registration,
-      blink::WebSyncUnregistrationCallbacks* callbacks);
+      blink::WebSyncUnregistrationCallbacks* callbacks) override;
   void getRegistration(
       blink::WebSyncRegistration::Periodicity,
       const blink::WebString& tag,
       blink::WebServiceWorkerRegistration* service_worker_registration,
-      blink::WebSyncRegistrationCallbacks* callbacks);
+      blink::WebSyncRegistrationCallbacks* callbacks) override;
   void getRegistrations(
       blink::WebSyncRegistration::Periodicity periodicity,
       blink::WebServiceWorkerRegistration* service_worker_registration,
-      blink::WebSyncGetRegistrationsCallbacks* callbacks);
+      blink::WebSyncGetRegistrationsCallbacks* callbacks) override;
   void getPermissionStatus(
       blink::WebSyncRegistration::Periodicity periodicity,
       blink::WebServiceWorkerRegistration* service_worker_registration,
-      blink::WebSyncGetPermissionStatusCallbacks* callbacks);
+      blink::WebSyncGetPermissionStatusCallbacks* callbacks) override;
   // TODO(jkarlin): Rename to releaseRegistrationHandle.
-  void releaseRegistration(int64_t handle_id);
+  void releaseRegistration(int64_t handle_id) override;
 
   void DuplicateRegistrationHandle(
       int handle_id,
       const BackgroundSyncService::DuplicateRegistrationHandleCallback&
           callback);
 
  private:
   // Callback handlers
   void RegisterCallback(
       scoped_ptr<blink::WebSyncRegistrationCallbacks> callbacks,
@@ skipping 20 matching lines @@
 
   ServiceRegistry* service_registry_;
   BackgroundSyncServicePtr background_sync_service_;
 
   DISALLOW_COPY_AND_ASSIGN(BackgroundSyncProvider);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_BACKGROUND_SYNC_BACKGROUND_SYNC_PROVIDER_H_