common: Add cr50 into factory shim

Only mask the two largest directories (/opt/google/chrome and
/opt/google/containers) in factory shim image, so that cr50 is included
in factory shim.

BUG=b:118821734
TEST=build factory shim and check there is /opt/google/cr50

Change-Id: I4a571b5a33b3549d37f26e01b468c5e7ebea43b0
Reviewed-on: https://chromium-review.googlesource.com/1314231
Commit-Ready: Cheng-Han Yang <chenghan@chromium.org>
Tested-by: Cheng-Han Yang <chenghan@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2649296
Reviewed-by: Cheng-Han Yang <chenghan@chromium.org>
Commit-Queue: Cheng-Han Yang <chenghan@chromium.org>
1 file changed