The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/75cb7baf751b5497879ef21d4c0e5247188d5a7a

commit 75cb7baf751b5497879ef21d4c0e5247188d5a7a
Author: Jorge Lucangeli Obes <jorgelo@chromium.org>
Date: Wed Jul 12 00:48:04 2017

debugd: Don't set half-constructed command lines.

If |sandboxing_| is true but |user_| or |group_| are not set, the
cmdline will be incomplete, and subsequent calls to Init() will make
things worse. Same thing if |set_capabilities_| is true but
|sandboxing_| is false or |user_| is root.

Fix this by returning false before the cmdline is built.

BUG= chromium:739736 
TEST=Chrome OS boots, chrome:system works.

Change-Id: I3eb01428b796097b434612c049240d38d97296fc
Reviewed-on: https://chromium-review.googlesource.com/561638
Commit-Ready: Jorge Lucangeli Obes <jorgelo@chromium.org>
Tested-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>

[modify] https://crrev.com/75cb7baf751b5497879ef21d4c0e5247188d5a7a/debugd/src/sandboxed_process.cc