[Feed] Fork RequestThrottler.

Bug: 831648
Change-Id: I3a9525384ca17c05f38748fc3592af3f46f742db
Reviewed-on: https://chromium-review.googlesource.com/1089930
Commit-Queue: Sky Malice <skym@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Reviewed-by: Filip Gorski <fgorski@chromium.org>
Reviewed-by: Patrick Noland <pnoland@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579566}
10 files changed