The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cc3e7e5ac51c7e608c768ab6c73bcad81a3daee2

commit cc3e7e5ac51c7e608c768ab6c73bcad81a3daee2
Author: Matt Falkenhagen <falken@chromium.org>
Date: Tue Aug 28 06:23:48 2018

service worker: Don't throttle again after network fallback.

Throttles can defer the request and possibly impact performance.
There's evidence of this happening like issue 817909.

Before this CL, service worker network fallback would incur throttling
twice. This CL adds RestartWithFactory to ThrottlingURLLoader to make
network fallback a lightweight internal swap of the destination factory
after throttling already occurred.

Bug:  873575 ,  876983 
Change-Id: Icd44fdf13a27ad1a95e39a6640f7ce0c15cd9184
Reviewed-on: https://chromium-review.googlesource.com/1189250
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586598}
[modify] https://crrev.com/cc3e7e5ac51c7e608c768ab6c73bcad81a3daee2/content/browser/loader/navigation_url_loader_impl.cc
[modify] https://crrev.com/cc3e7e5ac51c7e608c768ab6c73bcad81a3daee2/content/common/throttling_url_loader.cc
[modify] https://crrev.com/cc3e7e5ac51c7e608c768ab6c73bcad81a3daee2/content/common/throttling_url_loader.h