Fix coreboot project-specific pre-upload hooks

- Coreboot is now a public repo, and is named
  "chromiumos/third_party/coreboot", not "chromeos...".
- Add Signed-off-by presubmit check, since it's a requirement upstream.

BUG=chromium:338878
TEST=Verified that coreboot commit without sign-off was caught by presubmit.
Verified that adding sign-off allowed presubmit pass.

Change-Id: I6be53109ac278f90004538e5984f8715354ba9f8
Reviewed-on: https://chromium-review.googlesource.com/184250
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Stefan Reinauer <reinauer@google.com>
Commit-Queue: Shawn Nematbakhsh <shawnn@chromium.org>
Tested-by: Shawn Nematbakhsh <shawnn@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index ac34055..9ec5d1d 100755
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -702,8 +702,6 @@
     "chromeos/overlays/chromeos-partner-overlay": [_check_manifests],
     "chromeos/platform/ec-private": [_run_checkpatch_ec,
                                      _check_change_has_branch_field],
-    "chromeos/third_party/coreboot": [_check_change_has_branch_field,
-                                      _check_google_copyright],
     "chromeos/third_party/intel-framework": [_check_change_has_branch_field],
     "chromeos/vendor/kernel-exynos-staging": [_run_checkpatch,
                                               _kernel_configcheck],
@@ -715,6 +713,9 @@
                                _check_change_has_branch_field],
     "chromiumos/platform/mosys": [_check_change_has_branch_field],
     "chromiumos/platform/vboot_reference": [_check_change_has_branch_field],
+    "chromiumos/third_party/coreboot": [_check_change_has_branch_field,
+                                        _check_change_has_signoff_field,
+                                        _check_google_copyright],
     "chromiumos/third_party/flashrom": [_check_change_has_branch_field],
     "chromiumos/third_party/kernel": [_run_checkpatch, _kernel_configcheck],
     "chromiumos/third_party/kernel-next": [_run_checkpatch,