I have the following Colt barrels - all are chrome lined in both the bore and chamber (verified by visual inspection).
Barrel 1: early M16 production upper, 20" 1x12 - marked "C" on the bottom of the barrel, no other markings
Barrels 2&3: made in 91 for the israelis - new in original wrap with hebrew labels, 20" 1x12 - marked "C MP CHROME BORE"
Barrel 4: (not colt, but also chrome bore and chamber 1x12), 20" 1x12 - marked "SAK MP B" (Saco)
Barrel 5: M16A2 profile from a civvie production Colt Sporter II, 20" 1x7 - marked "C MP 5.56 NATO 1/7"
Barrel 6: Bushmaster post-ban civilian production upper from 1998 - marked "B MP 5.56 NATO 1/9 H BAR"
I also have one colt civvie production barrel that doesn't appear to have a chrome bore - just the chrome chamber. It's a 16" M4 profile marked "C MP 5.56 NATO 1/9"
So, if it's a military contract barrel, it's chrome lined whether it says so or not. If it's civilian production, it MIGHT be chrome lined, even if it doesn't say so - just have to look at it and take your chances.