A note about such devices, completely aside form whether Disney allows them or not.
We have an Anker one. It gets HOT when charging things. If you read through the mountain of
Amazon reviews you will discover that they had a period where some would get so hot they would actually **melt things** including in some cases part of the device, but especially surfaces they were on.
There were also a slew of media reports over the years of "third party" USB chargers for Apple devices that would overheat and in some cases even start fires. Apple even issued some statements about those ones. We bought our Anker one before the reports of the melting came out, so we are very very cautious with it.
I therefore don't fully trust them and ONLY use them when an adult human is around/in the same room. So, no plug in and leave it while I go do things elsewhere in the house or even worse leave the house. We don't bring ours on the cruise.
If they were made by a reputable brand name like Belkin I would have more trust in the product, but Belkin doesn't make devices in that style. Likewise if the product was by a name I don't recognize but sold at e.g. the Apple Store as approved for their products. Instead they are made by these third parties who you have never heard of and who only sell online.
A safer solution which works for us:
I have about 4 external battery charger things. Depending on their capacity they will charge most USB-chargeable devices [be careful buying them if you have something like an iPad that has a larger current draw to make sure the external battery you are contemplating will meet its power needs]. So, for example, the ones I have will recharge my iPhone fully about 4 times. Each one can charge two devices at a time.
So, I charge up the external batteries using the available power sockets in the room --- I only ever need to have two charging at a time, max. I then use the external batteries to charge my devices. We only use the original manufacturer's (OEM) charging cables that came with our devices for ANY charging.
The external batteries are also handy when out and about. I can put one in my bag, along with the OEM cable(s) for the devices. Allows me to charge in the bag or at a destination. Forgot to charge the phone overnight ? Plug it into the battery, toss the two in the bag and in an hour or two you have a charged phone.
We do have a couple Belkin adapters that plus right into an outlet and give you e.g. one power plug + 2 USB ports. the problem is when you don't have unobstructed access to the outlet it won't fit. IIRC the cruise outlets are slightly recessed and/or have other obstructions that may preclude using something like those.
=====
Ok, I just did a quick search at the Apple store and discovered a new Belkin product !! Yeah !!!! Once I am done this post I will be buying one and tossing our Anker multiport charger. Obviously I have never used it so can't speak to this Belkin, but nice to see they have multi-port USB chargers now.
Belkin Family RockStar™ 4-Port USB Charger:
http://www.apple.com/ca/shop/product/HKJD2ZM/A/belkin-family-rockstar-4-port-usb-charger
http://www.belkin.com/us/p/P-F8M990/
Amazon sells it as do others.
SW