The Timeline panel is now called the Performance panel. This change was introduced in Chrome 58. You can see what version of Chrome you’re running by typing chrome://version into the URL bar.
I write the official DevTools docs. That doc is old. I need to redirect it to the up-to-date docs, or add a deprecation notice to it.
Get Started With Analyzing Runtime Performance teaches you how to diagnose forced synchronous layouts, using the Performance panel. Note that the workflow and UI are different than the tutorial that you referenced, but the new workflow ultimately achieves the same goal of diagnosing and finding forced synchronous layouts.