Taking a quick test spin. Seems to be enabled (on mac) by the existing "Gemini in Chrome" extension but requires a Chrome update. Which has a global shortcut (across all mac apps) of "Ctrl+g" (this can be changed). The additional AI features seem to come from the tab content's integration into the Gemini console (previously (I believe) the Gemini extension was merely a thin console to the Gemini service)).

The direct tab integration works by first showing the Gemini console (ctrl-g or Gemini icon in the mac system tray) where there is then a 'Share current page' icon below the text view.

This adds a blue border around the chrome window indicating the current page can be shared with chrome. It's not clear, but I believe the page content is only shared once a prompt is made intending to use the page's content. However, the share-enablement remains enabled for all tabs (all tab windows will have the blue border) until turned off in the Gemini consol. Again, it's not clear if just merely browsing these tabs will automatically share that content with Google.

The Gemini integration does not perform actions (can't ask it to do stuff directly with the site's content (navigate, click buttons, etc).

But direct summarization works well (try it on an HN comment page or news article).

Overall, I like this feature as long as I understand what and when things are being shared and ability to turn off easily.