Cannot download URIs with a "filesystem:" scheme

I can reliably reproduce the issue. The URL we get from oxide (in the webview’s onDownloadRequested handler) is of the form: "filesystem:https://web.telegram.org/temporary/xxxxx.jpg". Not sure where that "filesystem:" prefix comes from.

It appears the 'filesystem' URI scheme is deprecated and should probably not be used: http://www.iana.org/assignments/uri-schemes/historic/filesystem.

An image (or any other type of file) with a "filesystem:" URL is already stored on disk (using the filesystem API) and the "https://web.telegram.org/temporary/xxxxx.jpg" part of the URL doesn’t represent an actual valid URL, just a unique identifier that the filesystem API uses to retrieve the file in its cache.

Not sure how to address this issue in oxide/webbrowser-app.

I'm not sure how to address this either - other schemes that point to content within Oxide won't work too (eg, blob:). I imagine that the Android webview has the same limitation here.

Android Chrome does not have this limitation; photoeditorsdk.com downloads a blob URL (as described in bug #1563035) and the export button works as expected in Chrome on Android; the image is downloaded.

Stuart: would you happen to know how the android webview component (the one based on chrome, but not chrome the application) behaves in that regard? I don’t have an android device handy atm so I can’t test this myself.

I've just tried the same thing in the in-app Twitter browser and it does not download. I do not know whether this is because the webview can't handle it or because the webview handles it fine and then gives the data to the Twitter app itself, which does not know what to do with it. (If you can think of a better way of testing, I'm happy to do so.)

Thanks for the feedback Stuart.
According to https://developer.chrome.com/multidevice/webview/overview#does_the_new_webview_have_feature_parity_with_chrome_for_android_, the chrome webview doesn’t support the filesystem API.