SAN Franciscans upset over dirty streets, growing homelessness, and a troubled economy voted incumbent Mayor Art Agnos out of office on Dec. 10 and picked former police chief Frank Jordan instead.Mr. Jordan, a quiet-spoken campaigner who promised to get this politically liberal city "back on track," will be sworn into office in January. A conservative Democrat who spent 33 years on the police force, Jordan promised to unite the city of 720,000. Some liberal leaders in the city eyed Jordan's victory with caution, saying that some of his supporters could harden public attitudes toward minorities and the disadvantaged. "I'm saying if Frank Jordan does not manage the city, San Francisco could become a racist city," said the Rev. Cecil Williams, pastor of Glide Memorial Methodist Church and an activist in the black community. It was a disappointing outcome for Mayor Agnos, who was swept into City Hall four years ago with 70 percent of the vote.