Suggestions: Use net::BackoffEntry instead of hand-rolled exponential backoff

Also improves tests by properly injecting a clock.

Bug: 762473
Change-Id: Idc10843adfaea8ddc0496e9c1276ca656e3ac1b1
Reviewed-on: https://chromium-review.googlesource.com/666927
Commit-Queue: Marc Treib <treib@chromium.org>
Reviewed-by: Mathieu Perreault <mathp@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#502500}
5 files changed