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- Previously SmbService and SmbFileSystem initialized their
temp_file_manager_ members via a Task which was run on a non-UI thread.
Changes to the class state should only happen on the UI thread to avoid
race conditions.

Bug: 879911
Change-Id: If79b0cd1162d2080c9ec1d44b0beb62cc53e8278
Reviewed-on: https://chromium-review.googlesource.com/1208193Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Commit-Queue: Bailey Berro <baileyberro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589077}