Add most recently used mount URL to File Share URL in SMB add dialog

- The text field for File Share URL will now initialize to the most
  recently used share path.

Bug: chromium:887133
Test: end to end
Change-Id: Ic59f7d34332b25c0e28832c6109060b849e838f2
Reviewed-by: Steven Bennetts <>
Reviewed-by: Bailey Berro <>
Commit-Queue: jimmy gong <>
Cr-Commit-Position: refs/heads/master@{#604418}
7 files changed