The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7fc07bf6ad2ad5e2a12b21d99c84d4562026f71c

commit 7fc07bf6ad2ad5e2a12b21d99c84d4562026f71c
Author: Gauthier Ambard <gambard@chromium.org>
Date: Tue Jan 02 09:58:03 2018

Fix PRESUBMIT check for ARC guard

The check is failing because it was written as if the content of the
file returned with f.NewContents() is a string. It is actually a list.
This CL fixes it.

The check never worked.

Bug:  798289 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Icfd216bbcaee78671878b65ac412b9063bd24509
Reviewed-on: https://chromium-review.googlesource.com/847372
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#526452}
[modify] https://crrev.com/7fc07bf6ad2ad5e2a12b21d99c84d4562026f71c/ios/PRESUBMIT.py
[modify] https://crrev.com/7fc07bf6ad2ad5e2a12b21d99c84d4562026f71c/ios/PRESUBMIT_test.py