cryptohome: Delete the right path when overriding with a passthrough dir.

The relative path |tracked_dir| now starts from "root/" or "user/",
hence the base directory must be one level up from the "user" directory.

BUG=chromium:729997
TEST=crs_workon_make cryptohome --test
TEST=Manual step shown in the bug

Change-Id: If91d17c8897c4d4c8c77c86d4e46d62f429c75dd
Reviewed-on: https://chromium-review.googlesource.com/526833
Commit-Ready: Kazuhiro Inaba <kinaba@chromium.org>
Tested-by: Kazuhiro Inaba <kinaba@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
(cherry picked from commit 51dd8de2eea1697ce6f0e4b813751000998cd147)
Reviewed-on: https://chromium-review.googlesource.com/527744
Reviewed-by: Kazuhiro Inaba <kinaba@chromium.org>
Commit-Queue: Kazuhiro Inaba <kinaba@chromium.org>
Trybot-Ready: Kazuhiro Inaba <kinaba@chromium.org>
3 files changed