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

cloud_print/service/win/chrome_launcher.h

Index: cloud_print/service/win/chrome_launcher.h
diff --git a/cloud_print/service/win/chrome_launcher.h b/cloud_print/service/win/chrome_launcher.h
index 073add75d7423b7a54000132ea5489854ec56de1..189bbc740c2c87bae92866e59e4d4de52fbd6ec3 100644
--- a/cloud_print/service/win/chrome_launcher.h
+++ b/cloud_print/service/win/chrome_launcher.h
@@ -17,12 +17,13 @@ class ChromeLauncher : public base::DelegateSimpleThread::Delegate {
  public:
   explicit ChromeLauncher(const base::FilePath& user_data);
 
-  virtual ~ChromeLauncher();
+  ~ChromeLauncher() override;
 
   bool Start();
   void Stop();
 
-  virtual void Run() override;
+  // base::DelegateSimpleThread::Delegate:
+  void Run() override;
 
   static std::string CreateServiceStateFile(
       const std::string& proxy_id,