Intent to Extend Origin Trial: Cross-origin opener policy reporting API

Skip to first unread message

Camille Lamy

Sep 23, 2020, 10:17:29 AM9/23/20
to blink-dev

Contact emails



Design docs


Adds a reporting API to help developers deploy cross-origin opener policy.

Blink component


Search tags

COOPCOOP reporting

TAG review

TAG review status



Interoperability and Compatibility

This is a new feature.

Gecko: No signal

WebKit: No signal

Web developers: No signals


This feature will be used with cross-origin opener policy, and often with cross-origin embedder policy (in particular, its reporting API).


The feature requires developers to properly set up a reporting endpoint. However it helps adoption of COOP by providing a report-only mode that developers can use to check that their websites will not break when enabling COOP.


The reporting API exposes that other pages tried to access cross-origin properties of the page.

Goals for experimentation

We want to gather feedback on whether the proposed data in the reports is helpful to developers to debug bugs with COOP.

Experimental timeline


Reason this experiment is being extended

We could not get our partners to experiment with the APi and provide us with feedback in the short timeframe of the trial (1 release). We're extending it by 2 releases to get the trial to run 3 releases, which should be enough time to get feedback.

Ongoing technical constraints



This should help with COOP debuggability as DevTools will be able to hook in the same places as we send reports and use this to surface useful information to developers trying to enable COOP.

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?

No All platforms will be supported except Android WebView. The underlying COOP feature requires multiple renderer processes which Android WebView cannot provide.

Is this feature fully tested by web-platform-tests?


Tracking bug

Link to entry on the Chrome Platform Status

Links to previous Intent discussions

Intent to prototype:

Yoav Weiss

Sep 24, 2020, 5:27:01 AM9/24/20
to Camille Lamy, blink-dev
LGTM to experiment till M88

You received this message because you are subscribed to the Google Groups "blink-dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email to
To view this discussion on the web visit
Reply all
Reply to author
0 new messages