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

chromeos/attestation/attestation_flow.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROMEOS_ATTESTATION_ATTESTATION_FLOW_H_
 #define CHROMEOS_ATTESTATION_ATTESTATION_FLOW_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "chromeos/attestation/attestation_constants.h"
 #include "chromeos/chromeos_export.h"
 #include "chromeos/dbus/dbus_method_call_status.h"
+#include "net/base/backoff_entry.h"
 #include "third_party/cros_system_api/dbus/service_constants.h"
 
 class AccountId;
 
+namespace base {
+
+class OneShotTimer;
+
+}  // namespace base
+
 namespace cryptohome {
 
 class AsyncMethodCaller;
 
 }  // namespace cryptohome
 
 namespace chromeos {
 
 class CryptohomeClient;
 
@@ skipping 70 matching lines @@
   //                   the existing key on success.
   //   callback - A callback which will be called when the operation completes.
   //              On success |result| will be true and |data| will contain the
   //              PCA-issued certificate chain in PEM format.
   virtual void GetCertificate(AttestationCertificateProfile certificate_profile,
                               const AccountId& account_id,
                               const std::string& request_origin,
                               bool force_new_key,
                               const CertificateCallback& callback);
 
+  // Sets the retry timer for tests.
+  void SetRetryTimerForTest(std::unique_ptr<base::OneShotTimer> retry_timer);
+
  private:
   // Asynchronously initiates the attestation enrollment flow.
+  // If attestation is not ready yet, retry as needed.
   //
   // Parameters
   //   on_failure - Called if any failure occurs.
+  //   next_task - Called on successful enrollment.
+  void InitiateEnroll(const base::Closure& on_failure,
+                      const base::Closure& next_task);
+
+  // Called when atestation is not prepared yet, to re-initiate enrollment
+  // after a delay.
+  //
+  // Parameters
+  //   on_failure - Called if any failure occurs.
+  //   next_task - Called on successful enrollment.
+  void RetryInitiateEnroll(const base::Closure& on_failure,
+                           const base::Closure& next_task);
+
+  // Called when attestation is prepared, to start the actual enrollment flow.
+  //
+  // Parameters
+  //   on_failure - Called if any failure occurs.
   //   next_task - Called on successful enrollment.
   void StartEnroll(const base::Closure& on_failure,
                    const base::Closure& next_task);
 
   // Called when the attestation daemon has finished creating an enrollment
   // request for the Privacy CA.  The request is asynchronously forwarded as-is
   // to the PCA.
   //
   // Parameters
   //   on_failure - Called if any failure occurs.
@@ skipping 94 matching lines @@
   //   callback - Called when the operation completes.
   void GetExistingCertificate(AttestationKeyType key_type,
                               const AccountId& account_id,
                               const std::string& key_name,
                               const CertificateCallback& callback);
 
   cryptohome::AsyncMethodCaller* async_caller_;
   CryptohomeClient* cryptohome_client_;
   std::unique_ptr<ServerProxy> server_proxy_;
 
+  int16_t initiate_enroll_retries_ = 7;  // -1 is unlimited retries.

[apronin1, 2016/12/02 01:36:24]

don't we want unlimited retries by default? why 7 is a good magic number here?
also, it may make sense to let the caller pass this value to constructor

+  std::unique_ptr<base::OneShotTimer> retry_timer_;
+  net::BackoffEntry retry_backoff_;
+
   base::WeakPtrFactory<AttestationFlow> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AttestationFlow);
 };
 
 }  // namespace attestation
 }  // namespace chromeos
 
 #endif  // CHROMEOS_ATTESTATION_ATTESTATION_FLOW_H_