1825079 - HTMLInputElement's handling of MIME types in `accept` is awkwardly placed

Status: NEW

(Core :: DOM: Core & HTML, task)

Description

[Ray Kraesig [:rkraesig]]

HTMLInputElement transforms MIME types into extension-based filters before passing them along to nsIFilePicker. However, this is not desired on Android, where the native "file picker" uses MIME types directly, and does not support extension-based filters. The current workaround is simply to feed any supplied raw MIME types to nsIFilePicker alongside the resultant extension-globs; Android ignores the latter and the desktop OSes ignore the former.

This is strongly indicative of an abstraction-layer mismatch. We should probably refactor this so that the transformation happens in the nsIFilePicker implementation(s) rather than in HTMLInputElement — and then only on the platforms that require it.