Was rethinking why I add this methods here is cause I though the gridmanager is the one that knows about apps. And the icon should know how to render and so on.

In fact, when an app is updated (as you comment https://github.com/mozilla-b2g/gaia/pull/10033#issuecomment-18542106), we pass a new icon descriptor, that contains all the info to the icon to render.

So would like to keep it like that, unless you have strong opinion about this :)