First of all, that is factually incorrect -- Trump received 28.1% of the vote in Santa Clara county, which is significantly lower than 1/3rd. Source: https://results.enr.clarityelections.com/CA/Santa_Clara/1225....
Second of all, your bar for "essentially pro-Trump" being 1/3rd of the vote is ridiculous, by your standard almost every county in America is "essentially pro-Trump".