I'd like to take over this bug.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d27deff18dd90c3e95c7d3cefc6da6e004beeb92

commit d27deff18dd90c3e95c7d3cefc6da6e004beeb92
Author: Gyuyoung Kim <gyuyoung@igalia.com>
Date: Thu Jan 17 01:11:41 2019

s13n: Remove SigninManager-related includes from chrome_browser_main_android.cc

There are no uses of SigninManager|SigninManagerFactory in ChromeBrowserMainPartsAndroid.
So we don't need to keep the signin_manager.h and signing_manager_factory.h
includes in chrome_browser_main_android.cc.

Bug:  920203 
Change-Id: Ia43fe0fd75fe8ee2af9038bc4eaeb5419683d687
Reviewed-on: https://chromium-review.googlesource.com/c/1414210
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Cr-Commit-Position: refs/heads/master@{#623489}
[modify] https://crrev.com/d27deff18dd90c3e95c7d3cefc6da6e004beeb92/chrome/browser/chrome_browser_main_android.cc