This is awesome Kan-Ru, nice work.
I did a similar analysis a while back which is what led me to start
drafting this Webview spec
http://benfrancis.github.io/webview/
I think there could be a lot of value in a standard <webview> element and
the existing implementations are close enough that I think it wouldn't be
too hard to reach consensus on a common subset of the APIs.
I think the biggest obstacle is going to be that we still don't have a web
standard way of safely exposing this API to the web. If we reached
consensus on the <webview> element and API, we'd still be lacking a way to
expose it to the web to make it part of the web platform.
Is it worth approaching Google and Microsoft about working towards a
standard, even with this piece missing? I've already had conversations with
the people working on Google's implementation in the past and would be
happy to follow up with them. Could hosted packaged apps be a candidate for
that missing piece?
Even if making <webview> a new standard element for the web is some way
off, I still think the transition from <iframe mozbrowser> to <webview> in
Gecko is long overdue. I've been wondering whether we could start by
creating a <moz-webview> polyfill using Web Components, so that <webview>
could be reserved for a future standardised version?
Ben