This is needed to implement a new metric that measures
health of Web Page Replay archives.

Bug: chromium:880432

Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I59aed22e4671e491fc3a30d04fbdce1643404b32
Reviewed-on: https://chromium-review.googlesource.com/1204570
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55716}