Add option to allow web nfc api

[JulianVennen]

It would be very nice if there was an option to enable the web NFC API.
Currently, when trying to use it, you get a permission denied error.

Here's a demo site if you want to test it: https://googlechrome.github.io/samples/web-nfc/

[nktnet1]

Hey @JulianVennen,

Apart from Chrome, can you find any other browsers that supports this? (preferably based on the Android System WebView).

As an aside, FireFox doesn't yet.

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I can see that this site lists WebView as supported from version 89:

• https://developer.mozilla.org/en-US/docs/Web/API/Web_NFC_API#browser_compatibility

While these sites says otherwise (although may not be up to date):

• https://chromestatus.com/feature/6261030015467520
• https://caniuse.com/webnfc

However, I haven't been able to find much info on how to implement it (without relying on Android bridges).

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Since Webview Kiosk uses the underlying system webview, support is completely dependent.

[JulianVennen]

When I created this PR, I assumed this was just a simple permission check that was missing, but after digging deeper, it seems like there's some other magic that needs to be done. Webview never calls handlePermissionRequest for the NFC permission, even after ensuring the app itself has NFC permissions. I think this might unfortunately just not be possible with webview.

These browsers work:

• Chrome
• Edge

These browsers appear to have the classes but always throw the permission error:

• Opera
• WebView Kiosk
• DuckDuckGo
• Via Browser
• Fulugris

These browsers do not have the classes:

• Firefox

Samsung Internet oddly has the classes but doesn't give a permission error or scan any tags successfully.

[nktnet1]

Yeah, unfortunately, I don't see a way around this.

I found this issue just now:

• Android WebView Permission w3c-cg/web-nfc#650 (comment)

Where beaufortfrancois stated that:

click to view text

Web NFC is not supported in Android Webview. It's mainly due to the fact that Chrome Web NFC shows a prompt in Chrome and prompts are not implemented in Android WebView.