Validate Vary header for HTTP/2 pushed stream.

Validate request against Vary header for HTTP/2 pushed stream if
response headers are available at the time of request matching.

Bug: 554220
Change-Id: I0b7404b0157f35673a7709008d71a33f9a127377
Reviewed-on: https://chromium-review.googlesource.com/1015512
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Bence Béky <bnc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551906}
3 files changed