[whatwg] RWD Heaven: if browsers reported device capabilities in a request header

[divya manian]

This is the info I would love to see any time for my app to make the
kind of decision it should:
* connection speed: so I know how fast my resources can load, how quickly.
* bandwidth caps: so I know I shouldn't be sending HD images.
* battery time: network requests are a drain on battery life, if I
know before hand, I can make sure the user gets information in time.
* notification of change of any of these: so I can provide scaled up
experiences when these alter.

Feature testing would be sufficient for me to test support for various
standards, and ideally that should be something like this
http://dev.w3.org/csswg/css3-conditional/ for all open web
technologies. And based on my knowledge of the above I can provide a
decent experience for the user.

Screen resolution is something users have to work with. This is how it
has been on desktop and I suppose how this should work on mobile
rather than trying to detect it server side.

But yeah it seems like none of what I want can ever be provided
without a significant change in how ISPs, mobile data providers, etc
work. :||||