Chrome lined barrels generally last longer because they are better able to resist certain conditions that tend to erode the bore... Conditions like the heat caused during shooting, rust, moisture, fouling from powder and copper, general corrosion, and even beyond all that just general wear.
Some people also say that chrome lined barrels will retain accuracy longer than non-chrome lined (assuming proper care and no over cleaning)... I tend to basically agree with this.
Chrome lined barrels are also easier to clean, because stuff doesn't really stick to the chrome.
Also remember that non-chromed barrels need to be cared for a little more. I have some AR-15 uppers from the 1970's who's barrels need to be regularly cared for (every 2 months) even though they are just sitting there and not being shot. What I found was that unless I do a nice cleaning-lube-protectant regiment on them bi-monthly that they begin to develop small rust spots. ---With a modern non-chromed barrel you wont have to care for them as much as I do with these ones from the 1970's... but you should at the very least do a nice cleaning, lube, and rust protentant 1-2 times a year IF the guns not being used. Just my $0.02