Add metrics to track HTTP/0.9 usage for main frames and subresources

This will tell us how many more error pages we'll be showing if we
remove support for it.

TBR=mmenke@chromium.org
NOTRY=true
NOPRESUBMIT=true
NOWEARHAT=true
BUG=624462

Review-Url: https://codereview.chromium.org/2119623002
Cr-Commit-Position: refs/heads/master@{#404673}
(cherry picked from commit 8210acc6749feb3d372cd1aa0456eabe029a03af)

Review-Url: https://codereview.chromium.org/2140253002
Cr-Commit-Position: refs/branch-heads/2785@{#97}
Cr-Branched-From: 68623971be0cfc492a2cb0427d7f478e7b214c24-refs/heads/master@{#403382}
10 files changed