Supporting undo at all seems a bit odd. Supporting undo after the page closes seems wrong. Supporting undo after the browser restarts seems impossible.

I'm able to reproduce CTRL+Z undo'ing the delete after the chrome://settings/passwords tab is closed and then reopened. However, after all windows in the browser are closed and the browser is restarted, CTRL+Z no longer restores the deleted password.

From a security POV, this is outside of the threat model (https://chromium.googlesource.com/chromium/src/+/master/docs/security/faq.md#Why-arent-physically_local-attacks-in-Chromes-threat-model) but this is something that we should consider cleaning up (e.g. disable undo after 1 minute or the tab closes) for privacy reasons.

Given how easy it is to shoot oneself in the foot with deleting passwords, I agree that we should support Ctrl+Z for a short time and before closing the tab, but not beyond that.

Making undo possible via CTRL+Z was a deliberate choice to improve accessibility, as the clickable undo toast disappears after a few seconds. The underlying undo manager has its lifetime tied to a profile instance, so closing all tabs associated with a given profile will make it impossible to restore passwords via CTRL+Z.

However, I do agree that this is likely too robust and we maybe should add a timeout and listen events firing when the settings tab closes.