... or that they clicked on a link from the search results to a non-https website about backpacks or pressure cookers.
Say, I don't know, Amazon, where even if you try to visit it as https it redirects you to http.
* edit: On second thought, I'm not buying it. The whole thing reads too much like a bad police procedural. Thomas's commentary more or less sums up my thoughts on it: https://news.ycombinator.com/item?id=6141113
And since Google is https now, that means the feds have a realtime hook into the data.