Network Error Logging: Fill in protocol field

If ALPN protocol negotiation gives us an answer, use that directly;
otherwise, we assume HTTP/1.1 if any response headers were received.

Bug: 748549,833996
Change-Id: I33d6217ede6202358acf1a343296f5019a9b6052
Reviewed-on: https://chromium-review.googlesource.com/998021
Commit-Queue: Douglas Creager <dcreager@google.com>
Reviewed-by: Julia Tuttle <juliatuttle@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#551505}(cherry picked from commit 4467e5809ee40582965e5378d9094b4f70b7dd60)
Reviewed-on: https://chromium-review.googlesource.com/1028091
Cr-Commit-Position: refs/branch-heads/3396@{#293}
Cr-Branched-From: 9ef2aa869bc7bc0c089e255d698cca6e47d6b038-refs/heads/master@{#550428}
4 files changed