The article seems to say and show that once you prompt it searches your history by page titles and can then dig deeper into the top hits. The permissions in Chrome seem to agree with this:

> History search, powered by AI Use everyday language to search your browsing history and find sites you visited. You can also ask questions and get answers based on your browsing history.

> When you search browsing history, your history searches, the page content of best matches, and generated model outputs are sent to Google

It's also worth noting enabling history awareness is a separate toggle from having Gemini enabled, and it doesn't seem to be able to answer anything about history when I turn it off. Sharing the currently open pages also seems to be a separate permissions toggle from either of these.