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

content/browser/plugin_service_impl.h

Index: content/browser/plugin_service_impl.h
diff --git a/content/browser/plugin_service_impl.h b/content/browser/plugin_service_impl.h
index fae8dda1f3a6188fc34056c352d6d208ba0af698..1d419e09dead02283c91cd174de0daffcf7bb9d0 100644
--- a/content/browser/plugin_service_impl.h
+++ b/content/browser/plugin_service_impl.h
@@ -111,9 +111,9 @@ class CONTENT_EXPORT PluginServiceImpl
 #if defined(OS_MACOSX)
   void AppActivated() override;
 #elif defined(OS_WIN)
-  virtual bool GetPluginInfoFromWindow(HWND window,
-                                       base::string16* plugin_name,
-                                       base::string16* plugin_version) override;
+  bool GetPluginInfoFromWindow(HWND window,
+                               base::string16* plugin_name,
+                               base::string16* plugin_version) override;
 
   // Returns true iff the given HWND is a plugin.
   bool IsPluginWindow(HWND window);