cryptohome: Add MigrateKeyRequest protobuf.

This adds a protobuf to be used for the MigrateKeyEx dbus method in
cryptohome.

BUG=chromium:211405
TEST=test_that -b ${BOARD} platform_CryptohomeMigrateKey

Change-Id: Ib4a1a5622b7b3f363970b9e5e0dd584b33ddbf43
Reviewed-on: https://chromium-review.googlesource.com/1087835
Commit-Ready: Greg Kerr <kerrnel@chromium.org>
Tested-by: Greg Kerr <kerrnel@chromium.org>
Reviewed-by: Andrey Pronin <apronin@chromium.org>
2 files changed