Review of Permissions Policy ACTION-2191

I reviewed Permissions Policy 
(https://www.w3.org/TR/permissions-policy-1/), formerly called Feature 
Policy.

This spec provides a way for content to declare whether certain features 
should be allowed to operate in the browser. From the examples, it seems 
this is mainly intended so a page including content in an iframe can 
limit what the iframe content can do, in order to avoid hijacking of 
features controlled by the container content. But it could also be used 
for a page to limit browser features for itself.

Even after reading it, I'm not sure if there is an accessibility issue. 
If any of the features that can be turned off are important to 
accessibility, then there is a concern, but otherwise it might be this 
spec is too low-level for us to worry about. The list of features 
currently interacting with the policy is at:

https://github.com/w3c/webappsec-permissions-policy/blob/main/features.md

I *think* maybe those features don't cause an accessibility problem if 
turned off - they will be turned off for everybody, and they aren't 
otherwise required for access. If we agree with that, we can close this 
review with no comments. But if we can come up with a use case in which 
turning off a feature breaks accessibility, we should request an 
accessibility considerations statement warning authors to be smart about 
use of this, and spec developers for each feature to define what should 
happen for accessibility if a feature is turned off. I can draft such a 
statement, but would first like input on whether there is an issue or not.

Michael