CrOS FilesApp: Allow sharing of root of volume with crostini

Added 'share-with-linux' command to roots-context-menu and
directory-tree-context-menu so that root volumes can have
right-click > 'Share with Linux'.

Split valid root types out to have DriveFS as a separate
list so that they can be controlled with the DriveFS
feature flag.

Bug: 878324
Change-Id: Icbcd8f8fd709c8ccfd9cf87f902779731c8923e4
Reviewed-by: Luciano Pacheco <>
Commit-Queue: Joel Hockey <>
Cr-Commit-Position: refs/heads/master@{#603811}
5 files changed