LAS VEGAS — Earlier this week, during a phone interview from his Las Vegas hotel, Chris DeMarco practiced his first pep talk as a head coach. Fresh off his second season as a player-development coach, he recognizes that the biggest challenge of leading the Warriors' Summer League team will be managing players' expectations. "The Warriors are about people making sacrifices," said DeMarco, rehearsing the messaging he planned to deliver in one of his first team meetings. [...] the next week-plus is an opportunity for those not under contract with the Warriors to gain valuable experience. An impressive outing or two could earn them a training-camp invite with an NBA team. Though Golden State's roster is expected to reach the maximum of 15 within the next couple days, it could waive someone and clear the way for a spot on the prohibitive league favorites. A second-round pick from UNLV, he led Golden State with 15.8 points per game on 46.7 percent shooting (38.2 from three-point range) in Las Vegas last summer before carving out a rotation spot in the regular season. [...] as the only player on the Warriors' Summer League roster with significant NBA experience, he will be the...