This migrates chromium to the new mapping after testing it for V8 in 
https://chromium-review.googlesource.com/485579

Also switches dependent gclient configs. This will be a noop downstream.

Bug: 713356
Change-Id: Ic1cb4de139895021dfd35063a9d6c8e7a4e77b9d
Reviewed-on: https://chromium-review.googlesource.com/488604
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>