[BackgroundSync] Clean up some style nits and unnecessary checks

content/child/background_sync/background_sync_provider_thread_proxy.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_THREAD_PROXY_H_
 #define CONTENT_CHILD_BACKGROUND_SYNC_BACKGROUND_SYNC_PROVIDER_THREAD_PROXY_H_
 
 #include "base/macros.h"
 #include "content/child/worker_task_runner.h"
 #include "content/common/background_sync_service.mojom.h"
@@ skipping 20 matching lines @@
  public:
   static BackgroundSyncProviderThreadProxy* GetThreadInstance(
       base::SingleThreadTaskRunner* main_thread_task_runner,
       BackgroundSyncProvider* permissions_dispatcher);
 
   // blink::WebSyncProvider implementation
   void registerBackgroundSync(
       const blink::WebSyncRegistration* options,
       blink::WebServiceWorkerRegistration* service_worker_registration,
       bool requested_from_service_worker,
-      blink::WebSyncRegistrationCallbacks* callbacks);
+      blink::WebSyncRegistrationCallbacks* callbacks) override;
   void unregisterBackgroundSync(
       blink::WebSyncRegistration::Periodicity periodicity,
       int64_t 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);
-  void releaseRegistration(int64_t handle_id);
+      blink::WebSyncGetPermissionStatusCallbacks* callbacks) override;
+  void releaseRegistration(int64_t handle_id) override;
 
   // Given |handle_id|, ask the provider for a new handle with the same
   // underlying registration.
   void DuplicateRegistrationHandle(
       int64 handle_id,
       const BackgroundSyncService::DuplicateRegistrationHandleCallback&
           callback);
 
   // WorkerThread::Observer implementation.
   void WillStopCurrentWorkerThread() override;
@@ skipping 11 matching lines @@
   // and so should outlive the BackgroundSyncProviderThreadProxy, which is
   // created for a worker thread.
   BackgroundSyncProvider* sync_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(BackgroundSyncProviderThreadProxy);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_BACKGROUND_SYNC_BACKGROUND_SYNC_PROVIDER_THREAD_PROXY_H_