CrOS FilesApp: Change fmp.sharePathWithCrostini to take array of paths

chrome.fileManagerPrivate.sharePathWithCrostini changed name to
chrome.fileManagerPrivate.sharePathsWithCrostini and takes array
of Entry in order to simplify case where multiple paths are
being shared at a single time.

Requires a custom barrier closure in CrostiniSharePath to capture
the first instance of an error and respond with it when done.

Bug: 878324
Change-Id: I1f308028abda9db92990cc73ad8d7598aee118fe
Reviewed-on: https://chromium-review.googlesource.com/c/1293094
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Nicholas Verne <nverne@chromium.org>
Reviewed-by: Ben Wells <benwells@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602267}
19 files changed