Adding OpenFile/CloseFile to SmbFileSystem.

This change implements OpenFile and CloseFile in SmbFileSystem.

Bug: 757625
Test: Open and Close called manually via UI, producing expected results
Change-Id: Ib45025963afdaced2da646bda610e6a54b079f40
Reviewed-on: https://chromium-review.googlesource.com/840730
Commit-Queue: Bailey Berro <baileyberro@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#526013}
2 files changed