CHONGQING, China - Nine-year-old Anna He stands quietly amid the chaos in her boarding school dorm on a Sunday night, a frenzy of little girls chattering in Chinese as they change the linens on rows of wooden beds. Anna is an outsider here. Her parents are Chinese, but she cannot talk to her schoolmates because she grew up in America. This small girl with watchful dark eyes was at the center of one of the longest custody battles in the U.S. in recent times, a high-profile seven-year dispute marked by racial and cultural undercurrents. On one side were the Bakers,...