Clarify that ProxyDelegate tunnel methods are for HTTP/1.x

Bug: 926427
TBR: tbansal@chromium.org
Change-Id: Ic31bc0c40a1b21c45a3d5a47c13e07255a144234
Reviewed-on: https://chromium-review.googlesource.com/c/1457317
Commit-Queue: Wojciech Dzier┼╝anowski <wdzierzanowski@opera.com>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630046}
11 files changed