CSP and `picture`

Hi,

I've been working, together with the RICG[1], on the specification for the
`picture` element[2].
We need to decide which CSP directives will be applicable to `picture` and
its nested `source` elements.
Personally, I believe it would be easier for authors if the directive is
`img-src` (rather than `media-src`)

Do you guys have a preference in the matter?

Thanks,
Yoav


[1] http://responsiveimages.org
[2] http://www.w3.org/TR/html-picture-element/