If the remote MTP device is a smartphone, it does not provide files
until a user unlocks the device. The CL adds specific error message for
the situation.
BUG=26318917
Change-Id: Ic4c34609c55ec9c99b7b8a9143d6dae3835784e3
When MTP device is busy (e.g. used by other application),
MtpDocumentsProvider cannot open the device. The CL introduces specific
error message for the case.
BUG=26694828
Change-Id: Iffee2e1c554e4089601186469ff0eac2fd04decd
* Replace tentative resources with real ones.
* Show the notification for each device as per request from UX.
BUG=26625702
Change-Id: Ibcfe7075e4827d5aee216ce5c0007f6dd4572efe
