Chrome stopped spying on my browsing after I turned off this hidden panel

I thought Chrome’s privacy settings were already tight enough. I cleared history often, blocked cookies, and turned off every tracking option I could find. But the ads I saw still seemed to know exactly what I was doing. They lined up too closely with my recent searches, as if Chrome itself was quietly helping websites follow me around. So I looked more closely at Chrome’s menus and found a hidden panel I had completely overlooked.