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

chrome/browser/extensions/extension_storage_monitor_browsertest.cc

Index: chrome/browser/extensions/extension_storage_monitor_browsertest.cc
diff --git a/chrome/browser/extensions/extension_storage_monitor_browsertest.cc b/chrome/browser/extensions/extension_storage_monitor_browsertest.cc
index c4aebb0010209c93f5b17edd9a9c59a072b1bb82..d2a39668c3789b683d1dcc9cb9e845146895cbe8 100644
--- a/chrome/browser/extensions/extension_storage_monitor_browsertest.cc
+++ b/chrome/browser/extensions/extension_storage_monitor_browsertest.cc
@@ -36,9 +36,7 @@ class NotificationObserver : public message_center::MessageCenterObserver {
     message_center_->AddObserver(this);
   }
 
-  virtual ~NotificationObserver() {
-    message_center_->RemoveObserver(this);
-  }
+  ~NotificationObserver() override { message_center_->RemoveObserver(this); }
 
   bool HasReceivedNotification() const {
     return received_notifications_.find(target_notification_id_) !=
@@ -59,8 +57,7 @@ class NotificationObserver : public message_center::MessageCenterObserver {
 
  private:
   // MessageCenterObserver implementation:
-  virtual void OnNotificationAdded(
-      const std::string& notification_id) override {
+  void OnNotificationAdded(const std::string& notification_id) override {
     received_notifications_.insert(notification_id);
 
     if (waiting_ && HasReceivedNotification())
@@ -81,7 +78,7 @@ class ExtensionStorageMonitorTest : public ExtensionBrowserTest {
 
  protected:
   // ExtensionBrowserTest overrides:
-  virtual void SetUpOnMainThread() override {
+  void SetUpOnMainThread() override {
     ExtensionBrowserTest::SetUpOnMainThread();
 
     InitStorageMonitor();