I just noticed these lounge chairs in HKIA. I don’t believe they’ve been there for too long since I haven’t noticed them in the past.
The seats are located in the West Hall, right where the shuttle train leaves you. They’re spaced fairly evenly between gates 40 and 61, by the windows. It’s a great area to catch a nap since there’s not many people walking around on that side. I saw almost everyone sleeping on them as well, so a great place to catch some Zzzz or the view of passing planes.
Additionally, so you don’t run out of juice, the airport has charging points located all around various seating areas. Here is an example of a large one I saw, note that it only takes British type plugs, so you’ll need an adapter if coming from elsewhere. There’s also outlets in the floor which you can access from lifting the panel. They’re little rectangular squares in the carpeting.