Add a presubmit check to avoid commits to src/platform/libchromeos

libchromeos has been moved to src/platform2/. Nothing should get committed to
src/platform/libchromeos.

BUG=chromium:370258
TEST=Commit in libchromeos are rejected by the system.

CQ-DEPEND=CL:202334

Change-Id: I12743f6d4d90f2006b18d3fe33c51d06ab6731f9
Reviewed-on: https://chromium-review.googlesource.com/202440
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Tested-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Bertrand Simonnet <bsimonnet@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index 1b9a414..14be6ce 100755
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -863,6 +863,9 @@
     # TODO(bsimonnet): remove this check once src/platform/common-mk has been
     # removed from the manifest (crbug.com/379236).
     "chromiumos/platform/common-mk": [_moved_to_platform2],
+    # TODO(bsimonnet): remove this check once src/platform/libchromeos has been
+    # removed from the manifest (crbug.com/379939)
+    "chromiumos/platform/libchromeos": [_moved_to_platform2],
     "chromiumos/platform/ec": [_run_checkpatch_ec,
                                _check_change_has_branch_field],
     "chromiumos/platform/mosys": [_check_change_has_branch_field],