The behavior for browsers without support is to show the google.com/amp URL as before, along with a small html-based bar with additional information about the original domain and share intents.
Yeah, I didn't think so.
Does that mean that the Google+ button is coming back? Seriously? Why not just serve the content and leave it at that? Is the tiny bit of extra data you get from a unique "share on Facebook" URL worth it?
> The Navigator.share() method invokes the native sharing mechanism of the device as part of the Web Share API.