Republican Meg Whitman, the former chief executive of eBay, has edged ahead of state Attorney General Jerry Brown in the race for the California governor’s seat, according to a Field Poll conducted March 9-15. Whitman leads Brown, 46 percent to 43 percent, with 11 percent undecided. While that advantage falls within the poll’s 3.7 point margin of error, it is a big change from January when Brown led, 46 percent to 36 percent, with 18 percent undecided.