run mtpd in more namespaces

BUG=None
TEST=plugged in phone and Files.app could still see it via mtp

Change-Id: I581d457f2cc3b209436a2e02cef4c7b574a7c6de
Reviewed-on: https://chromium-review.googlesource.com/393166
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Shuhei Takahashi <nya@chromium.org>
2 files changed