Remove consent file if owned by root.
Remove consent file if owned by root.

As a precaution, remove the consent file if it had at one point been created
by this script (i.e. rather than through the browser).

BUG=chrome-os-partner:3655
TEST=gmerge'd the script and rebooted successfully.  Manually tested the new code.

Change-Id: I79c06b93427687ca948b21bd030d69cadb419c87
Reviewed-on: http://gerrit.chromium.org/gerrit/2696
Reviewed-by: Michael Krebs <d6638659c20694b0807ba6fa35ee0bac2e482e0f@chromium.org>
Tested-by: Michael Krebs <d6638659c20694b0807ba6fa35ee0bac2e482e0f@chromium.org>
(cherry picked from commit 0d667ec736136a0c67273e44200ab5a9f0142304)
Reviewed-on: http://gerrit.chromium.org/gerrit/2758

joshfire/chromiumos-platform-login_manager,joshfire/chromiumos-platform-login_manager,joshfire/chromiumos-platform-login_manager