[Chips] Don't force aria-checked attribute on choice/filter chips

[vanessanschmitt]

Angular Material is experimenting with MDC-backed chips. We are using a custom adapter, and we recently implemented the setAttr method that was added to the adapter interface in #4736.

I saw that setAttr is being used by the chip foundation here to toggle the aria-checked attribute for choice and filter chips. The MDC specs were updated so that choice chips now have role="radio" and filter chips have role="checkbox".

aria-checked makes sense in these contexts, but we are not using these roles for our own choice/filter chips. Ours have role="option" (the container chip set has role="listbox"). We therefore toggle aria-selected, and aria-checked doesn't make sense. Right now we are working around this with a check in setAttr to no-op if the attribute is aria-checked. angular/components#16530

We may consider in the future adding radio and checkbox interaction patterns, but we would still be keeping our current option/listbox pattern alongside them. Since aria-checked assumes certain roles, could you consider not managing aria-checked in MDC and instead leaving it up to the developer?

[jelbourn]

Chiming in to confirm that I agree aria-checked is too specific here, since the "Filter chips" part of the spec is very much a listbox pattern.

[patrickrodee]

Thanks for filing this issue. I'm open to any suggestions on how to achieve this.

[patrickrodee]

FYI the a11y spec for chips lists selectable chips (like filter) as being role="checkbox"

https://docs.google.com/document/d/1b0A08XkeRfKojc-6dccEXYPaUTy7ALHYg8D0-kAU_hU/edit#heading=h.g6fqgtabqq5g (link is only accessible to Googlers)

[vanessanschmitt]

@stevenyxu