Minor change to support bidirectional port mapping

Change-Id: I650d6df01f471f5f896a4fdfd48b6f3db939231e
Reviewed-on: https://chromium-review.googlesource.com/1170314
Commit-Queue: Stephan Stross <stephanstross@google.com>
Reviewed-by: Kevin Marshall <kmarshall@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#582727}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: d687c01622be947b5b4285138744a80882dba370
1 file changed