Add OVERRIDE to content/.

BUG=104314
TEST=no change

Review URL: http://codereview.chromium.org/8587009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110544 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/content/renderer/render_thread_impl.h b/content/renderer/render_thread_impl.h
index e3fdac3..615161a 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -169,7 +169,7 @@
   scoped_refptr<base::MessageLoopProxy> GetFileThreadMessageLoopProxy();
 
  private:
-  virtual bool OnControlMessageReceived(const IPC::Message& msg);
+  virtual bool OnControlMessageReceived(const IPC::Message& msg) OVERRIDE;
 
   void Init();