Standardize usage of virtual/override/final specifiers.

ash/screensaver/screensaver_view.h

Index: ash/screensaver/screensaver_view.h
diff --git a/ash/screensaver/screensaver_view.h b/ash/screensaver/screensaver_view.h
index 2a5bf6e3845bbe8a27a731e08c6239a25d669914..3fb2cdfd5413d55797e76abcb62d4c15f1677e22 100644
--- a/ash/screensaver/screensaver_view.h
+++ b/ash/screensaver/screensaver_view.h
@@ -47,13 +47,13 @@ class ScreensaverView : public views::WidgetDelegateView,
   friend class test::ScreensaverViewTest;
 
   explicit ScreensaverView(const GURL& url);
-  virtual ~ScreensaverView();
+  ~ScreensaverView() override;
 
   // views::WidgetDelegate overrides.
-  virtual views::View* GetContentsView() override;
+  views::View* GetContentsView() override;
 
   // content::WebContentsObserver overrides.
-  virtual void RenderProcessGone(base::TerminationStatus status) override;
+  void RenderProcessGone(base::TerminationStatus status) override;
 
   void Show();
   void Close();