This brainstorm is listed under devices. It is a hardware proposal, which is why it isn't applicable to any current devices. You won't be able to do it on your current devices. Don't even try.

The idea is, that when you plug your future device (with HDMI out) to a monitor, you don't have to get a separate charger to keep the device juiced up, but it will charge itself from the HDMI connection instead.