Standardize usage of virtual/override/final in content/

content/public/test/test_notification_tracker.h

Index: content/public/test/test_notification_tracker.h
diff --git a/content/public/test/test_notification_tracker.h b/content/public/test/test_notification_tracker.h
index 69d59fae17880747dd51f3085eddb966d61313c5..786ec147e05ebc6c095f3cf3ca979f44c3822d05 100644
--- a/content/public/test/test_notification_tracker.h
+++ b/content/public/test/test_notification_tracker.h
@@ -33,7 +33,7 @@ class TestNotificationTracker : public NotificationObserver {
   // ListenFor for the notifications you are interested in.
   TestNotificationTracker();
 
-  virtual ~TestNotificationTracker();
+  ~TestNotificationTracker() override;
 
   // Makes this object listen for the given notification with the given source.
   void ListenFor(int type, const NotificationSource& source);
@@ -69,9 +69,10 @@ class TestNotificationTracker : public NotificationObserver {
   const Event& at(size_t i) const { return events_[i]; }
 
  protected:
-  virtual void Observe(int type,
-                       const NotificationSource& source,
-                       const NotificationDetails& details) override;
+  void Observe(int type,
+               const NotificationSource& source,
+               const NotificationDetails& details) override;
+
  private:
   NotificationRegistrar registrar_;