The Real Bookmark Navigator 作者： Vietnam Regulator

ctrl+alt+→ will take you to the next bookmark, while ctrl+alt+← will take you to the previous bookmark. This currently allows for browsing through folders as well as looping from the last to the first or first to last bookmark in your toolbar. If a website has been deleted or the link has changed slightly, or if there is a redirect, the extension will remain on that "index" and you will be able to continue to navigate forwards or backwards.
There is also a basic popup if you pin the extension, which allows you to click to the next/previous bookmark.