Is there a guideline for a download task on an Android? Let's say, user initiates an app download on an Android (not from Apps app but from a 3d party app). What are the expected control on a "Downloading" window? I would assume [X] to quit the download. Is there an established guideline?
Typically downloads on Android are handled with a notification, so the user can get on and do other things while the download progresses. Sometimes this uses a toast for notification when it's completed.
In the Play Store they also use a progress bar with the following UI:
This is just contained inline, replacing the [Accept/Download] button after the user clicks it - there's no separate window needed. Incidentally, when the download is completed the user is presented with two options: [Open] and [Uninstall].