Agreed. If it's in direct response to a user action (a sync response to a click or a tap on an element smaller than 300x300px, for example), I think it's perhaps more legitimate to have a more visible indication, like a strip across the top. (I'd want the element size constrained to avoid issues with sites adding `onClick` handlers to the `<body>` element or similar.)
> Actually I think it makes sense to persistently show the notification icon in the navbar once the permission has been granted (same with mic, audio, and anything else) providing a quick glance at any privs that have been granted and an obvious way to revoke them.
I believe Firefox already does this. It also shows you privileges which you've explicitly denied -- for example, if you disallow location access, you'll see a slashed compass next to the (i) button in the Awesomebar.