Declare getFile() method as protected instead of private

Issue information

From user: stefan.korn

Contribution record

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Problem/Motivation

I would like to extend this module's functionality to delete a file on a custom media source type. If the getFile() method of this module would be protected instead of private, I could do this very easily by extending the MediaDeleteForm. Otherwise I would need to recreate the whole form class or at least big parts of it.
Not sure why the method is made private, hopefully switching to protected instead would be possible.

Steps to reproduce

na

Proposed resolution

I provide a small patch