Standardize usage of virtual/override/final in chrome/browser/sync_file_system/

chrome/browser/sync_file_system/drive_backend/register_app_task.h

Index: chrome/browser/sync_file_system/drive_backend/register_app_task.h
diff --git a/chrome/browser/sync_file_system/drive_backend/register_app_task.h b/chrome/browser/sync_file_system/drive_backend/register_app_task.h
index 063dfabcb648760168ddc01147102347d5dd260e..2bd628eab24a65d3a816acb30df8d0406c1cbad6 100644
--- a/chrome/browser/sync_file_system/drive_backend/register_app_task.h
+++ b/chrome/browser/sync_file_system/drive_backend/register_app_task.h
@@ -34,10 +34,10 @@ class TrackerIDSet;
 class RegisterAppTask : public ExclusiveTask {
  public:
   RegisterAppTask(SyncEngineContext* sync_context, const std::string& app_id);
-  virtual ~RegisterAppTask();
+  ~RegisterAppTask() override;
 
   bool CanFinishImmediately();
-  virtual void RunExclusive(const SyncStatusCallback& callback) override;
+  void RunExclusive(const SyncStatusCallback& callback) override;
 
  private:
   void CreateAppRootFolder(const SyncStatusCallback& callback);