Let me remove Mac label since OWP feature request should not be an OS specific.

I'm really not sure if I understand the request correctly.
But if you just want to send and receive MIDI messages from Chrome, it's exactly what Web MIDI provides. Chrome is no more MIDI device than other DAW applications are.

If you want to communicate among DAW applications and Chrome, you could use IAC driver that macOS provides.
(FYI http://www.soundonsound.com/techniques/mac-os-x-tiger-musicians-guide)

If you are saying that you want to play Web Audio based synthesizer via Web MIDI from native DAW applications. That makes sense, and there is a spec discussion at W3C. But I decided not to go without other browsers catching up.
https://github.com/WebAudio/web-midi-api/issues/45
https://github.com/WebAudio/web-midi-api/issues/124

Thanks for the change an sorry about that.

What I'm talking about is Chrome being recognized in the midi.inputs and outputs with a unique ID.
For the moment DAWS and Chrome works the same way they are a MIDI io matrix for devices and virtual MIDI port(s).
The aim would be Chrome being a virtual MIDI device on his own.
(see Loopback port)

Hey, ranjitkan@, why milestone is needed for a unconfirmed P3 feature request?

indricorp@, we need to discuss the spec and reach a consensus with other working group members beforehand. But this will need installing a specially designed device driver on Windows. So, we probably need to make sure that the use case is really important for many users.

toyoshim@ Is there a way to participate to this discussion?
Do I need to open a specific topic somewhere?

I already showed links in the comment 3.

Since this is a feature request, marking it as untriaged.