chromium: Move fetchurl calls to getChannel

We always do something like "fetchurl channelProduct", so let's move it
to getChannel directly so we can avoid those fetchurl calls all over the
place.

Also, we can still access subattributes from the fetchurl call if we
need to, so there really is no need to expose the product's attributes
directly.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>