Update {virtual,override,final} to follow C++11 style in chrome/browser/chromeos/app_mode.

chrome/browser/chromeos/app_mode/kiosk_external_update_validator.h

Index: chrome/browser/chromeos/app_mode/kiosk_external_update_validator.h
diff --git a/chrome/browser/chromeos/app_mode/kiosk_external_update_validator.h b/chrome/browser/chromeos/app_mode/kiosk_external_update_validator.h
index 3d58a9d4e40a71e5c3aebf231530b0b4c4abc995..4058d404c4780dc2cd6f31218752e828b4fcdac9 100644
--- a/chrome/browser/chromeos/app_mode/kiosk_external_update_validator.h
+++ b/chrome/browser/chromeos/app_mode/kiosk_external_update_validator.h
@@ -48,15 +48,15 @@ class KioskExternalUpdateValidator
   void Start();
 
  private:
-  virtual ~KioskExternalUpdateValidator();
+  ~KioskExternalUpdateValidator() override;
 
   // SandboxedUnpackerClient overrides.
-  virtual void OnUnpackFailure(const base::string16& error_message) override;
-  virtual void OnUnpackSuccess(const base::FilePath& temp_dir,
-                               const base::FilePath& extension_dir,
-                               const base::DictionaryValue* original_manifest,
-                               const extensions::Extension* extension,
-                               const SkBitmap& install_icon) override;
+  void OnUnpackFailure(const base::string16& error_message) override;
+  void OnUnpackSuccess(const base::FilePath& temp_dir,
+                       const base::FilePath& extension_dir,
+                       const base::DictionaryValue* original_manifest,
+                       const extensions::Extension* extension,
+                       const SkBitmap& install_icon) override;
 
   // Task runner for executing file I/O tasks.
   const scoped_refptr<base::SequencedTaskRunner> backend_task_runner_;