I would like to take over this bug.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6918e47e2ed076fba9f38ad60b6bc14d60659378

commit 6918e47e2ed076fba9f38ad60b6bc14d60659378
Author: Gyuyoung Kim <gyuyoung@igalia.com>
Date: Tue Jan 15 06:54:51 2019

s13n: Remove an unnecessary SigninManager related include in external_component_loader.cc

There are no uses of SigninManager in external_component_loader.cc.

Bug:  920212 
Change-Id: I4a4beb437f275c936153d912193245b4b5869ba8
Reviewed-on: https://chromium-review.googlesource.com/c/1410812
Reviewed-by: Ben Wells <benwells@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Cr-Commit-Position: refs/heads/master@{#622761}
[modify] https://crrev.com/6918e47e2ed076fba9f38ad60b6bc14d60659378/chrome/browser/extensions/external_component_loader.cc