Return container_path from CrostiniSharePath

This field is used after sharing path to then determine what the
backup path will be for tremplin running in termina.

Bug: 912638
Change-Id: I9c9b4a36b17015cfb8c13746898a49ad8788e63d
Reviewed-on: https://chromium-review.googlesource.com/c/1414253
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Nicholas Verne <nverne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623561}
3 files changed