Re: Benjamin Carlyle http 2.0 expression of interest

Chromium does not use SPDY PING as a keepalive mechanism. That just
unnecessarily wakes up the radio on mobile devices. We send PING when we
have not sent anything over the SPDY session in awhile and we're about to
send a SYN_STREAM frame. This is a liveness check, which is very different
from a keepalive. Therefore, we do not have metrics about "how many PING
are actually needed to keep-alive" since we don't actually try to do
keepalive.