clean up SmbFileSystem member variables

This change includes some cleanup, removing unused member variables and
removing a reference to a bug that has been fixed.

Bug: chromium:757625, chromium:796334
Change-Id: I6a5901f355050a47aeb59850e34ed463b79b6899
Reviewed-on: https://chromium-review.googlesource.com/978379
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Commit-Queue: Zentaro Kavanagh <zentaro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545494}
2 files changed