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

chrome/browser/printing/print_preview_message_handler.h

Index: chrome/browser/printing/print_preview_message_handler.h
diff --git a/chrome/browser/printing/print_preview_message_handler.h b/chrome/browser/printing/print_preview_message_handler.h
index ad72e8721f35dd58346cf13cf401af02f2f1fbdb..e91dc3d14ae88304143629585e4558bb52dd041c 100644
--- a/chrome/browser/printing/print_preview_message_handler.h
+++ b/chrome/browser/printing/print_preview_message_handler.h
@@ -33,10 +33,10 @@ class PrintPreviewMessageHandler
     : public content::WebContentsObserver,
       public content::WebContentsUserData<PrintPreviewMessageHandler> {
  public:
-  virtual ~PrintPreviewMessageHandler();
+  ~PrintPreviewMessageHandler() override;
 
   // content::WebContentsObserver implementation.
-  virtual bool OnMessageReceived(const IPC::Message& message) override;
+  bool OnMessageReceived(const IPC::Message& message) override;
 
  private:
   explicit PrintPreviewMessageHandler(content::WebContents* web_contents);