Warn on missing OVERRIDE/virtual everywhere, not just in header files.

chrome/browser/ui/webui/print_preview/print_preview_handler.cc

Index: chrome/browser/ui/webui/print_preview/print_preview_handler.cc
diff --git a/chrome/browser/ui/webui/print_preview/print_preview_handler.cc b/chrome/browser/ui/webui/print_preview/print_preview_handler.cc
index 777560e32f3a8ba69313e1f8287164725d6d85e5..d895b7ee338b8abbbb99bf7f7d586ce970c33153 100644
--- a/chrome/browser/ui/webui/print_preview/print_preview_handler.cc
+++ b/chrome/browser/ui/webui/print_preview/print_preview_handler.cc
@@ -302,14 +302,14 @@ class PrintPreviewHandler::AccessTokenService
     }
   }
 
-  void OnGetTokenSuccess(const OAuth2TokenService::Request* request,
-                         const std::string& access_token,
-                         const base::Time& expiration_time) OVERRIDE {
+  virtual void OnGetTokenSuccess(const OAuth2TokenService::Request* request,
+                                 const std::string& access_token,
+                                 const base::Time& expiration_time) OVERRIDE {
     OnServiceResponce(request, access_token);
   }
 
-  void OnGetTokenFailure(const OAuth2TokenService::Request* request,
-                         const GoogleServiceAuthError& error) OVERRIDE {
+  virtual void OnGetTokenFailure(const OAuth2TokenService::Request* request,
+                                 const GoogleServiceAuthError& error) OVERRIDE {
     OnServiceResponce(request, std::string());
   }