What if there was a situation where someone had no water to drink or food to eat. Would it be safe for them to drink their own urine? What are the possible risks of doing this? Could there be any benefits?
If you are in a no-other-liquid situation then not, it's not safe to drink. The problem is that your urine is a way to remove superfluous minerals and other stuff from the body. The body's job, especially in a state of dehydration, is to remove this waste with the least amount of water sufficient to flush it away.
If you then drink this urine, you are ingesting back all the salts you just got rid of. You are not getting your liquid-to-salts ratio better, you are making it worse. So when you are already dehydrated, you get dehydrated even quicker if you drink your urine.
If you are at no risk of dehydration (you can additionally ingest sufficient water from drinks or food), then the above does not apply. As long as you don't have an urinary tract infection, your urine is also sterile, so you are not at risk of infection either. This makes urine safe to drink.
There are people who drink urine (outside of dehydration situations) for supposed health benefits, but I have never heard of any evidence that such benefits exist.
I don't know of peer reviewed sources for this, but the dangers of drinking urine for survival are both logical from a theoretical view point and common knowledge in outdoor lore, for example see http://survivalcache.com/water-purification/.
The Outdoors site has the same question, with a suggestion for a possible purification method which might remove the dissolved minerals. But urine is also rich in organic compounds and starts breeding bacteria almost immediately upon leaving your body. So I'd be weary to try it: fresh urine is safe, but urine which has stood around at room temperature isn't.