Revert "Partially Revert 2b9d2417"

This reverts commit 71818c84.
This patch was created because the upstream update_engine was using
the new version of libchrome and the Chrome OS one was not. Now
that we are upreving libchrome on Chrome OS we can revert this.

BUG=b:37434548
TEST=Build
CQ-DEPEND=CL:1240033

Change-Id: I98b7d124212087292500701782de08b3d3ecc559
Reviewed-on: https://chromium-review.googlesource.com/1239818


Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>