eugenebut@ could you PTAL?

I tested on iPhone SE and iPad Air 2 and accessibility announcements work as expected. The app reads the text when UI is presented or download is completed. Interacting with the app cause accessibility system to describe the label, which can interrupt previously spoken announcements (which is WAI). 

Watching this video and a video from another bug, it appears that accessibility announcement is cut by the progress bar, which is a bug (not RBS though).

Gauthier, do you know why |stopProgressBar| method sets progress to 1 before hiding the progress indicator?

Do you think it shouldn't?
I think the idea is to show to the user that the loading of the page is completed, so you visually finish the loading of the progress bar.

My question would be more: Should the progress bar get the voice over focus when its progress is updated?

Laura, Chrome for iOS has an issue where loading progress bar receives accessibility focus, announces the progress (like "0 percent complete" or "100 percent complete") and this announcement interrupts other voice over announcements. Do you think it is useful to focus on progress bar when it gets updated?

Laura, do you have any feedback on comment #5? Thanks!

Hey, really sorry for the delay -- no I don't think it's useful to steal focus here, or interrupt the user with multiple progress updates if they have shifted their focus elsewhere. I think it's most helpful to announce when progress begins and ends, but not necessarily give repeated updates in between (e.g. 40%, 50%) unless the user places focus on the progress bar to specifically check in on progress. 

Laura, this bug happens because the progress bar is focused when progress ends. Seems like we have 2 options here: 
 - do not focus on progress bar when 100% is reached
 - remove "File download is available" accessibility announcement
which one do you think is preferable? Thanks!

So the progress bar is focused once it finishes no matter what the user is doing? I wouldn't have it steal focus, as that could be really disruptive. 

Correct, progress bar is focused once it finishes. Gauthier, do you think we can make progress bar smarter about updating accessibility label?

The accessibility label of the progress bar is done by MDC, so I don't think we have lot of possibility to really customize it.
The current behavior is to post a notification when the progress bar is shown. But the notification takes some time (~2s) to steal the focus. If the page is loading too quickly, the focus is stolen after the page finish loading.

We could file a feature request to the MDC team to have the possibility to avoid this focus. It means the loading bar would never steal focus, the user would have to manually focus it.
WDYT?

Yes, I think filing the feature request sounds good and would be respectful of not stealing focus and disrupting the user. 

I have filed https://github.com/material-components/material-components-ios/issues/4470

Issue 736898 has been merged into this issue.