Intent to Extend Origin Trial: Web Components v0 Deprecation

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Mason Freed

Nov 30, 2020, 9:11:19 PM11/30/20
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Web Components v0 features were removed by default in M80, and the "deprecation extension" Origin Trial was available until M87. As of M88, which goes to the stable channel around mid-Jan, 2021, all OT support code has been removed. However, some users of the Origin Trial extension need a bit more time to migrate. I would therefore like to request an extension of the Origin Trial end date, to June 30, 2021. These users will continue using M87, and will not upgrade to M88. So this is not a request for additional milestones past M87, just an extension of the token end date itself.

Link to “Intent to Implement” blink-dev discussion

The intent to deprecate is here.

The original intent to experiment for the “deprecation extension” origin trial is here.

Goals for experimentation

Give sites a way to have more time to migrate, while allowing us to turn the feature off for everyone else sooner.

Experimental timeline

This experiment was available from M73 through M87, which is not changing via this request. The maximum end date is currently set to Feb 1, 2021, and this request is to extend that through June 30, 2021.

Any risks when the experiment finishes?

Yes, there is a risk. Sites that continue to use Web Components v0 features after the token expiration date will either break or (more likely) have a performance degradation.

Reason this experiment is being extended

Some users need additional time to migrate.

Ongoing technical constraints



Usages of the deprecated features are reported in the DevTools console.

Will this feature be supported on all five Blink platforms supported by Origin Trials (Windows, Mac, Linux, Chrome OS, and Android)?


Link to entry on the feature dashboard

Here are HTML Imports, Shadow DOM v0, and Custom Elements v0.

Chris Harrelson

Dec 1, 2020, 12:08:19 AM12/1/20
to Mason Freed, blink-dev

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