The way I understand that image: Each bar is the equivalent of a tab, and the linked circles are the visiting history for that tab.
The busy blue bar near the bottom shows that you visited six links, went back to the third link and visited four from there, then went back to the second of those four and visited one. The large size and white color of that one last circle means that it's what you're visiting now?
Or I'm totally off, and this is an alien interface in need of interpretation by Hoshi Sato.
Yup except for the large image, you got everything right.
The large image _was_ the topmost suggestion of autocompletion at the time. This one in particular was "search the string in the url-bar with duckduckgo". It does not exist anymore. It has been replaced with three neat columns that organize suggestions in a better way.
The busy blue bar near the bottom shows that you visited six links, went back to the third link and visited four from there, then went back to the second of those four and visited one. The large size and white color of that one last circle means that it's what you're visiting now?
Or I'm totally off, and this is an alien interface in need of interpretation by Hoshi Sato.