Intent to Experiment: COOP: restrict-properties

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Arthur Hemery

Jun 1, 2023, 3:20:01 AM6/1/23
to blink-dev

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Cross-Origin-Opener-Policy is used to sever the relationship between popup and openers, to increase security. "restrict-properties" is a proposed value that restricts the relationship instead of completely severing it. It would enable crossOriginIsolated when paired with COEP.

Blink component


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Interoperability and Compatibility

It could fail to become an interoperable part of the web platform if other browsers do not implement it. The OT is intended to gather user feedback to get support from Mozilla.

Gecko: No signal

WebKit: No signal

Web developers: No signals

Other signals: Have a few partners interested in trying this out like Zoom and Facebook, as well as a couple of internal partners (altimin@ for perfetto dashboards, vickyzhu@ for gmail, etc.).

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

Goals for experimentation

The goal for this experiment is to give partners the possibility to try the new value at scale and to discover potential deployment blockers that were not anticipated (e.g. external dependency, same-origin communications required, etc.)


COOP reporting will support restricted cross-origin properties reporting, similar to what exists for other COOP values.

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


COOP is parsed on all platforms, but the process model implied might vary.

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

Yes under wpt/html/cross-origin-opener-policy/tentative/restrict-properties.

Flag name


Requires code in //chrome?


Tracking bug

Launch bug

Estimated milestones

OriginTrial desktop last119
OriginTrial desktop first116
OriginTrial Android last119
OriginTrial Android first116

Link to entry on the Chrome Platform Status

Links to previous Intent discussions

Previous Intent to experiment, dropped because implementation was incomplete:
 to prototype:

Mike Taylor

Jun 1, 2023, 3:17:45 PM6/1/23
to Arthur Hemery, blink-dev

LGTM to experiment from M116 to M119 inclusive.

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Vipul Anant

Oct 19, 2023, 11:42:49 AM10/19/23
to blink-dev, Mike Taylor, Arthur Hemery
There are certain use cases that are not solved with postMessage and closed only. There is some requirement to focus (whenever user shifts to some other tab with popup opened in background) & close ( to avoid unnecessary popup window to be remained opened in background),so can we have hese calls supported focus() & close()?


Dec 6, 2023, 11:58:51 AM12/6/23
to blink-dev, Vipul Anant, Mike Taylor, Arthur Hemery
Hi team,
We have an application using SharedArrayBuffer for which we have started using COOP as restrict-properties. However, we are currently facing issue when we open any login pop up, we are not able to focus on it again if user clicks on login button in the main app.

It would be really good if we can get support for focus functionality.

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