It's common for some types of dialogs to have a suppression checkbox,

such as "Do not ask again." To ensure there's a standard approach for

this, dialogs can now have canSuppress=true set. This will place a

checkbox in the secondary actions area, at the far left.
The default text will be "Do not ask again," but this can be customized

by setting suppressText=.
It's up to the caller to determine how to suppress. The dialog doesn't

control any of this. It does provide the result of the checkbox though

as an isSuppressed property.
This will be used for upcoming confirmation utility dialogs.
Along with this, the ARIA role for modal dialogs has been updated to use

alertdialog. This will announce the dialog to screen readers, and is

the correct choice when popping up a modal dialog that requires

attention, rather than a utility dialog that is simply on screen.

Tested this along with the rest of the dialog changes, verifying that

the checkbox appears when configured and that the state can be handled.