I'd like to take over this bug.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0b503fbe90573b59267dc1a6730be67efa09086f

commit 0b503fbe90573b59267dc1a6730be67efa09086f
Author: Gyuyoung Kim <gyuyoung@igalia.com>
Date: Wed Jan 16 02:10:43 2019

s13n: Remove unnecessary oauth2_token_service.h|oquth2_mint_token_flow.h include from identity_api.h

indentity_api.h doesn't use anything related to OAuth2. So this CL removes unnecessary
includes of oauth2_foo.h files in identity_api.h.

Bug:  921604 
Change-Id: I3330ad8cfcf434f49aba792fef2616bf8895184e
Reviewed-on: https://chromium-review.googlesource.com/c/1410852
Reviewed-by: David Roger <droger@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Cr-Commit-Position: refs/heads/master@{#623035}
[modify] https://crrev.com/0b503fbe90573b59267dc1a6730be67efa09086f/chrome/browser/extensions/api/identity/identity_api.h