Do not handle impossible cases in SpdySession.

Clean up some corner cases concerning HTTP/2 pushed streams.  I plan to
add a histogram that records every possible outcome of receiving a
pushed stream, and it is cleaner if impossible cases are not handled
with an early return, but they are simply documented by a DCHECK.

Note that GetPromisedUrlFromHeaders() guarantees a lot of things about
the pushed request: if the scheme is not http or https, or if the method
is not GET or HEAD, then it returns an invalid URL.  Therefore there is
no need to handle these cases explicitly in SpdySession.  There is test
coverage in SpdyNetworkTransactionTest that enforces this.

Bug: 831536
Change-Id: Ic3dae56b026598fa2965c8eee0db02cfbc95eb06
Reviewed-on: https://chromium-review.googlesource.com/1055760
Commit-Queue: Bence Béky <bnc@chromium.org>
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558244}
1 file changed