How do I undo a close of a tab?
I have a workaround that leads to a solution but not a direct solution:

If you have Chrome tabs as separate entities in the Overview (Recent Apps) section, then undoing the closure of a tab is not possible. However, if you open Chrome and tap on the three-dotted menu in the right-hand corner and then tap Settings and navigate to Merge tabs and apps and move the slider to off then your tabs will appear under a seperate tab switcher inside Chrome (this is, I suspect, how your previous phone handled tabs). When you now close tabs, the option to undo the closure is visible.