Update {virtual,override,final} for base to follow C++11 style.

This patch was automatically generated using a variation of
https://codereview.chromium.org/598073004

BUG=417463

Review URL: https://codereview.chromium.org/842993002

Cr-Commit-Position: refs/heads/master@{#310660}
diff --git a/base/mac/scoped_sending_event_unittest.mm b/base/mac/scoped_sending_event_unittest.mm
index 95f6eba..02ef2db 100644
--- a/base/mac/scoped_sending_event_unittest.mm
+++ b/base/mac/scoped_sending_event_unittest.mm
@@ -27,9 +27,7 @@
   ScopedSendingEventTest() : app_([[ScopedSendingEventTestCrApp alloc] init]) {
     NSApp = app_.get();
   }
-  virtual ~ScopedSendingEventTest() {
-    NSApp = nil;
-  }
+  ~ScopedSendingEventTest() override { NSApp = nil; }
 
  private:
   base::scoped_nsobject<ScopedSendingEventTestCrApp> app_;