Farewell, advertising cookie. After years of debate, Apple and Google are making separate moves to effectively kill the software marketers use to track your online activity and tailor ads specifically for you. The moves are upending the way companies have reached audiences and made money from ads since the earliest days of the Internet. Apple’s plan has pleased privacy advocates but left mobile app developers, ad-tech firms and rivals (chiefly Facebook) worried and fuming. And Google is nearing a similarly contentious update to its Chrome browser, which will radically alter how ads are targeted on websites. With these changes, both companies are wielding the kind of power normally only governments have.