First, that is only in case Özkan builds a customized build of Chromium. Since Özkan has not noted whether this is a customized build of Chromium, I did not assume that.
Second, an extension is more portable and does not lock you to a specific/customized version (sometimes out of your budget/expertise), nor does it require making changes to a website (sometimes out of your control).
(Also, by writing that code, whether for a website or for an extension, you could easily use it for both of them)
Either way might work, but knowing more of the options is better. And there is no "right" answer so far, because it depends on the exact situation/goals of Özkan.