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>