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

chrome/browser/chromeos/attestation/platform_verification_flow.cc

Index: chrome/browser/chromeos/attestation/platform_verification_flow.cc
diff --git a/chrome/browser/chromeos/attestation/platform_verification_flow.cc b/chrome/browser/chromeos/attestation/platform_verification_flow.cc
index d13221bc8542a7ab958aa3c5f7022fa643ab30fd..91b3098c5cbaf91a7159cfdb8b7084ee9bd65479 100644
--- a/chrome/browser/chromeos/attestation/platform_verification_flow.cc
+++ b/chrome/browser/chromeos/attestation/platform_verification_flow.cc
@@ -161,7 +161,8 @@ PlatformVerificationFlow::PlatformVerificationFlow()
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   std::unique_ptr<ServerProxy> attestation_ca_client(new AttestationCAClient());
   default_attestation_flow_.reset(new AttestationFlow(
-      async_caller_, cryptohome_client_, std::move(attestation_ca_client)));
+      async_caller_, cryptohome_client_, std::move(attestation_ca_client),
+      base::TimeDelta::FromMinutes(1)));
   attestation_flow_ = default_attestation_flow_.get();
   default_delegate_.reset(new DefaultDelegate());
   delegate_ = default_delegate_.get();