Wait for the attestation to be ready (TPM being prepared for attestation) before trying to enroll.

chrome/browser/chromeos/attestation/attestation_policy_observer.cc

Index: chrome/browser/chromeos/attestation/attestation_policy_observer.cc
diff --git a/chrome/browser/chromeos/attestation/attestation_policy_observer.cc b/chrome/browser/chromeos/attestation/attestation_policy_observer.cc
index 933996d0a380597d102ff384f67cc09be24b476a..c2f81e9ed4399dea551a340f87d339ef38e82251 100644
--- a/chrome/browser/chromeos/attestation/attestation_policy_observer.cc
+++ b/chrome/browser/chromeos/attestation/attestation_policy_observer.cc
@@ -162,7 +162,7 @@ void AttestationPolicyObserver::Start() {
         new AttestationCAClient());
     default_attestation_flow_.reset(new AttestationFlow(
         cryptohome::AsyncMethodCaller::GetInstance(), cryptohome_client_,
-        std::move(attestation_ca_client)));
+        std::move(attestation_ca_client), base::TimeDelta::FromMinutes(1)));
     attestation_flow_ = default_attestation_flow_.get();
   }