Avoid crash on Files app when creating a directory

Files app crashes if a client document provider creates a file
in createDocument callback unexpectedly during the directory
creation sequence.

This CL fixes to avoid the crash on Files app and show a Snackbar
message instead.

Bug: 70246394
Change-Id: I27b8aac0306c505e9b1b57314e82122aeb968dc8
1 file changed