When Google offered me the job of Director of Android Platform Security in 2017, it was impossible to refuse. Yes, Trump was already president—my family and I had qualms—but he seemed contained, even ineffective. More importantly, Google was a different company 9 years ago. Android was open source first and had just surpassed 2 billion users. I’d been studying its security from the outside since 2009, and it was (and still is!) the most exciting end-user facing operating system to work on. Howev...