Standardize usage of virtual/override/final in gin/

gin/test/file_runner.h

Index: gin/test/file_runner.h
diff --git a/gin/test/file_runner.h b/gin/test/file_runner.h
index 5082cd59b15ff745cdfb4435a5c7dd2d6c1b3102..9f7ab4b02057c58a9ba2b39ac842470e18647020 100644
--- a/gin/test/file_runner.h
+++ b/gin/test/file_runner.h
@@ -20,12 +20,11 @@ namespace gin {
 class FileRunnerDelegate : public ModuleRunnerDelegate {
  public:
   FileRunnerDelegate();
-  virtual ~FileRunnerDelegate();
+  ~FileRunnerDelegate() override;
 
  private:
   // From ModuleRunnerDelegate:
-  virtual void UnhandledException(ShellRunner* runner,
-                                  TryCatch& try_catch) override;
+  void UnhandledException(ShellRunner* runner, TryCatch& try_catch) override;
 
   DISALLOW_COPY_AND_ASSIGN(FileRunnerDelegate);
 };