Update {virtual,override} to follow C++11 style in chrome.

chrome/utility/shell_handler_win.h

Index: chrome/utility/shell_handler_win.h
diff --git a/chrome/utility/shell_handler_win.h b/chrome/utility/shell_handler_win.h
index 729f111ead6fd2baad621193a712fc738db30b81..6c993f744a0fc82da019cb31f89b8743a851dd8b 100644
--- a/chrome/utility/shell_handler_win.h
+++ b/chrome/utility/shell_handler_win.h
@@ -30,10 +30,10 @@ struct ChromeUtilityMsg_GetSaveFileName_Params;
 class ShellHandler : public UtilityMessageHandler {
  public:
   ShellHandler();
-  virtual ~ShellHandler();
+  ~ShellHandler() override;
 
   // IPC::Listener implementation
-  virtual bool OnMessageReceived(const IPC::Message& message) override;
+  bool OnMessageReceived(const IPC::Message& message) override;
 
  private:
   void OnOpenFileViaShell(const base::FilePath& full_path);