Big Tech donors contributed historic sums to political campaigns up and down the ballot in California this primary season. But with votes being tallied in the wake of the Tuesday primary election, Silicon Valley’s efforts to influence the state’s elections appear to be meeting with mixed results.  In the closely watched governor’s race , San Jose Mayor Matt Mahan, who received millions from top tech executives, conceded only minutes after polls closed. Mahan raked in more donations from the tech industry than any other candidate in the gubernatorial primary , including from Google co-founder Sergey Brin and Patrick Collison, the co-founder and chief executive at fintech platform Stripe, among other big-tech figures. Yet with roughly 60% of ballots counted as of Friday afternoon, according to The Associated Press , Mahan has garnered just 4%, trailing the leading candidates in the race by more than 20 points. Tech entrepreneur Ethan Agarwal, whose bid to oust long-time Democratic Rep.…