SACRAMENTO — Officials in San Francisco, San Diego and Los Angeles counties will be able to expand conservatorship rules to give them more control over who can be involuntarily held for mental-health treatment. Gov. Jerry Brown signed SB1045 by Sen. Scott Wiener, D-San Francisco, on Thursday. The bill creates a five-year pilot program in the three counties intended to get more mentally ill people who suffer from substance abuse off the streets and into treatment. The bill was among 350 that were still on Brown’s desk before Thursday. Sunday is the deadline for the governor to act on bills. Wiener said SB1045 will give the three counties the tools they need to help mentally ill people. Brown signed the bill without comment.