The Offscreen converter is only required in Chromium in the background process. Otherwise, we can safely create an iframe (there are a number of document-based contexts)
We can avoid messing up with building offscreen documents where it is not required (for example, it was like this before the change in the settings page)
As it is related to the platform we can simplify access to converter, and clean up requiring permissions when it can be skipped
From my understanding: