Who makes chrome lined barrels besides Bushmaster? Thanks.

I believe Colt does.

Last I heard RRA was planning to start, don't know if it happened.

Armalite, Bushmaster, & Colt all manufacture chrome-lined barrels.  
Rock River Arms has also started making them; I bought one of their new chrome-lined barrels from Legal Transfers & it shoots great, better than I can.

ARMALITE!!!...

Only Armalite and Bushmaster chrome line their barrels as a standard feature.  If I remember right Colt only chrome lines their chamber.  

RRA and DPMS offer it as an option at a really reasonable price. Olympic Arms also offers chrome lining as an option, but it's a little too expensive as compared to the others.  Oly also use stainless steel for their M4 barrels.

Armalite will chrome line all but their Stainless Steet barrels.

Bushmaster will chrome line all berrels except the Stainless, DCM and Varminter.

Colt will chrome line all chambers, but only the bores of M4 and Govt Profile barrels.

DPMS will chrome line only on special order. Generally you cant find them, but currently some have been showing up for sale. DPMS must have just run a batch not too long ago.

Olymipic will only chrome line on special order at an added fee.

Rock River offers both chrome lined and non-chrome lined. If you want chrome, be sure to ask.