Provide RootClientTokenOwner into ClaimRootClientAuthToken

ClaimRootClientAuthToken will check if token is already claimed and
block claim if needed.

BUG=25766815

Change-Id: I8d12578c99307830afccd280c322d2240234e435
Reviewed-on: https://weave-review.googlesource.com/1934
Reviewed-by: Alex Vakulenko <avakulenko@google.com>
5 files changed