Remove dead session-manager GLib error constants

These are no longer used.

BUG=None
TEST=build
CQ-DEPEND=CL:201761

Change-Id: I2514e168e81e12eb9db74b43323f20d073996de4
Reviewed-on: https://chromium-review.googlesource.com/201760
Reviewed-by: Chris Masone <cmasone@chromium.org>
Commit-Queue: Chris Masone <cmasone@chromium.org>
Tested-by: Chris Masone <cmasone@chromium.org>
3 files changed