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

chrome/browser/drive/drive_app_registry_unittest.cc

Index: chrome/browser/drive/drive_app_registry_unittest.cc
diff --git a/chrome/browser/drive/drive_app_registry_unittest.cc b/chrome/browser/drive/drive_app_registry_unittest.cc
index cb1985a4b62f6abe44f451555649102fcab2c0de..71e8fbe82f352eb1375253fe076a72432c9330b0 100644
--- a/chrome/browser/drive/drive_app_registry_unittest.cc
+++ b/chrome/browser/drive/drive_app_registry_unittest.cc
@@ -25,15 +25,13 @@ class TestDriveAppRegistryObserver : public DriveAppRegistryObserver {
         update_count_(0) {
     registry_->AddObserver(this);
   }
-  virtual ~TestDriveAppRegistryObserver() {
-    registry_->RemoveObserver(this);
-  }
+  ~TestDriveAppRegistryObserver() override { registry_->RemoveObserver(this); }
 
   int update_count() const { return update_count_; }
 
  private:
   // DriveAppRegistryObserver overrides:
-  virtual void OnDriveAppRegistryUpdated() override { ++update_count_; }
+  void OnDriveAppRegistryUpdated() override { ++update_count_; }
 
   DriveAppRegistry* registry_;
   int update_count_;