I visit Furnitture Market at least twice a year and am up to speed on most brands and models out there. I can tell you that there is nothing on the market with a built-in keyboard and mouse (yet). However, if you are willing to pay for it, Fortress Seating has done a motorized table in their chairs that automatically folds out and back into the arm. I'm sure they could mount a keyboard on one or more of the trays. But, like I said, you are going to pay for this customization. If you are into DIY, you would probably mount a keyboard and mouse or keyboard with a built-in trackball to a tray table that is used on quite a few home theater chairs. See the Palliser Playback, Lane Matinee 103 and some others. The tray tables are stored in the armrests vertically and have room for a keyboard/mouse, so it wouldn't be hard to accomplish, especially if wireless.
Home Theater Seating and Decor
Home Theater Seating