Add mtp_storage_info.mojom file and modify the related code.

Define mojo format MtpStorageInfo to mirror the MTP protobuf message.
Use this struct in MediaTransferProtocolManager and related code.

This is a preparation work for MTP servicification.

BUG=769630

Change-Id: Ie435600271840e9a26f59dfb53952a2b07642749
Reviewed-on: https://chromium-review.googlesource.com/838372
Commit-Queue: Lei Zhang <[email protected]>
Reviewed-by: Colin Blundell <[email protected]>
Reviewed-by: Lei Zhang <[email protected]>
Reviewed-by: Will Harris <[email protected]>
Cr-Commit-Position: refs/heads/master@{#525828}
14 files changed