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

cloud_print/gcp20/prototype/privet_http_server.h

Index: cloud_print/gcp20/prototype/privet_http_server.h
diff --git a/cloud_print/gcp20/prototype/privet_http_server.h b/cloud_print/gcp20/prototype/privet_http_server.h
index 26fcdfb65952098157954884d3c434e521bfcac0..5f92d6806f305a95d0b0820ec4df3e1e884eb0b2 100644
--- a/cloud_print/gcp20/prototype/privet_http_server.h
+++ b/cloud_print/gcp20/prototype/privet_http_server.h
@@ -141,16 +141,15 @@ class PrivetHttpServer: public net::HttpServer::Delegate {
 
  private:
   // net::HttpServer::Delegate methods:
-  virtual void OnConnect(int connection_id) override {}
-  virtual void OnHttpRequest(
+  void OnConnect(int connection_id) override {}
+  void OnHttpRequest(
       int connection_id,
       const net::HttpServerRequestInfo& info) override;
-  virtual void OnWebSocketRequest(
+  void OnWebSocketRequest(
       int connection_id,
       const net::HttpServerRequestInfo& info) override;
-  virtual void OnWebSocketMessage(int connection_id,
-                                  const std::string& data) override;
-  virtual void OnClose(int connection_id) override;
+  void OnWebSocketMessage(int connection_id, const std::string& data) override;
+  void OnClose(int connection_id) override;
 
   // Sends error as response. Invoked when request method is invalid.
   void ReportInvalidMethod(int connection_id);