Singer/songwriters who show off catchy hooks and strong commercial potential during their acoustic days often end up with outside producers who tell the artists to leave the pop arrangements to them. And so for her fourth album, Southern California beach-pop queen Colbie Caillat enters the dance club scene, with veteran producers Max Martin and Babyface each giving their assigned tracks a contemporary sheen that pumps up the optimism in Caillat’s generally sunny disposition. “Try” mixes sadness with spirited gung-ho. “Never Gonna Let You” keeps traces of acoustic guitar. And the sly “Nice Guys” sounds like she’s reaching that commercial potential.