This is a demo for the non-cookie Storage Access API extension. See the related blog post and spec.

1. Be sure test-third-party-cookie-phaseout is enabled and restart your browser if needed.
2. Open the iframe site in its own tab and click somewhere on the page to register user interaction.
3. In this window, click 'Open Broadcast Channel' button and approve the permissions prompt.
4. In the other window click the same 'Open Broadcast Channel' button (no permission prompt is needed).
5. Send messages back and forth using the 'Send' button in either window. You should see each message noted as 'sent' or 'recieved' in the respective window.
6. The message was shared via Broadcast Channel using the SAA handle to access unpartitioned storage.
7. You can find the code for this site here, and the iframe here.