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

chrome/browser/extensions/convert_web_app_browsertest.cc

Index: chrome/browser/extensions/convert_web_app_browsertest.cc
diff --git a/chrome/browser/extensions/convert_web_app_browsertest.cc b/chrome/browser/extensions/convert_web_app_browsertest.cc
index 438c4146375456f4afbe964abd4de31cf639b87e..0d38ce48e7a16b03e3b46cc42cd3ced39dbcd785 100644
--- a/chrome/browser/extensions/convert_web_app_browsertest.cc
+++ b/chrome/browser/extensions/convert_web_app_browsertest.cc
@@ -41,9 +41,9 @@ class ExtensionFromWebAppTest
 
  private:
   // content::NotificationObserver
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) override {
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override {
     if (type ==
         extensions::NOTIFICATION_EXTENSION_WILL_BE_INSTALLED_DEPRECATED) {
       const Extension* extension =