Use case

We want to make our application more accessible. As part of that effort, we have been attaching tooltips/labels to buttons so that screen readers can read out more helpful descriptions to their users instead of the default "Button" or "Push Button".

Snackbar provides no way to do this easily, even for classes extending it.

Proposal

I would like the Flutter team to either:

1. Allow the ability to pass in a close button tooltip via the constructor. OR
2. Use MaterialLocalizations.closeButtonTooltip as the tooltip to the IconButton representing the close button on the Snackbar.