Revert "[DeviceSync v2] Force enrollment after SyncMetadata 404 errors"

This reverts commit 65e3049c.

Reason for revert: The root cause was found server-side; this workaround is no longer needed.

Original change's description:
> [DeviceSync v2] Force enrollment after SyncMetadata 404 errors
> 
> This is a mitigation put in place to handle 404 errors returned by the
> CryptAuth server during SyncMetadata requests. A 404 error is returned
> when the server cannot find an enrolled device with the same Instance
> ID.
> 
> Theoretically, this should never occur assuming that 1) we never run a
> v2 DeviceSync until the device has successfully enrolled using v2
> Enrollment and 2) the Instance ID does not rotate. Without this
> mitigation, the user will unsuccessfully try to sync until the next
> enrollment, which could be up to 30 days.
> 
> This fix will be removed when the root cause is uncovered.
> 
> Bug: 1092113, b/155642672
> Change-Id: Ibc766ad21d83d1ace26c5e8c6c45f3eed835da74
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2234126
> Reviewed-by: James Vecore <vecore@google.com>
> Commit-Queue: Josh Nohle <nohle@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#776330}

TBR=nohle@chromium.org,vecore@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1092113, b/155642672
Change-Id: I94ac09ca75aba101a800176c644beec4f9ace710
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2252622Reviewed-by: Josh Nohle <nohle@chromium.org>
Reviewed-by: James Vecore <vecore@google.com>
Commit-Queue: Josh Nohle <nohle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#779951}

chromeos/services/device_sync/cryptauth_v2_device_manager_impl.cc

@@ -294,21 +294,6 @@ void CryptAuthV2DeviceManagerImpl::OnDeviceSyncFinished(
 
   RecordDeviceSyncResult(device_sync_result);
 
-  // TODO(https://crbug.com/1092113): This is a workaround for the SyncMetadata
-  // 404 errors returned by the server when it cannot find an enrolled device
-  // with the same Instance ID. Theoretically, this should never occur assuming
-  // that 1) we never run a v2 DeviceSync until the device has successfully
-  // enrolled using v2 Enrollment and 2) the Instance ID does not rotate.
-  // Without this mitigation, the user will unsuccessfully try to sync until the
-  // next enrollment, which could be up to 30 days. Remove this code when the
-  // root cause is uncovered.
-  if (device_sync_result.result_code() ==
-      CryptAuthDeviceSyncResult::ResultCode::
-          kErrorSyncMetadataApiCallEndpointNotFound) {
-    scheduler_->RequestEnrollment(cryptauthv2::ClientMetadata::FAILURE_RECOVERY,
-                                  base::nullopt /* session_id */);
-  }
-
   scheduler_->HandleDeviceSyncResult(device_sync_result);
 
   base::Optional<base::TimeDelta> time_to_next_attempt = GetTimeToNextAttempt();

chromeos/services/device_sync/cryptauth_v2_device_manager_impl_unittest.cc

@@ -209,7 +209,6 @@ class DeviceSyncCryptAuthV2DeviceManagerImplTest
   }
 
   CryptAuthV2DeviceManager* device_manager() { return device_manager_.get(); }
-  FakeCryptAuthScheduler* scheduler() { return &fake_scheduler_; }
 
  private:
   // Adds the ClientMetadata from the latest DeviceSync request to a list of
@@ -456,27 +455,6 @@ TEST_F(DeviceSyncCryptAuthV2DeviceManagerImplTest,
   TimeoutWaitingForClientAppMetadataAndVerifyResult();
 }
 
-// TODO(https://crbug.com/1092113): Remove when bug is resolved.
-TEST_F(DeviceSyncCryptAuthV2DeviceManagerImplTest,
-       ScheduleEnrollmentAfterSyncMetadataEndpointNotFoundError) {
-  CreateAndStartDeviceManager();
-  RequestDeviceSyncThroughSchedulerAndVerify(
-      cryptauthv2::ClientMetadata::PERIODIC, base::nullopt /* session_id */);
-  SucceedGetClientAppMetadataRequest();
-
-  EXPECT_FALSE(scheduler()->IsWaitingForEnrollmentResult());
-
-  // Fail SyncMetadata request with 404 error.
-  FinishDeviceSyncAttemptAndVerifyResult(
-      0u /* expected_device_sync_instance_index */,
-      CryptAuthDeviceSyncResult(CryptAuthDeviceSyncResult::ResultCode::
-                                    kErrorSyncMetadataApiCallEndpointNotFound,
-                                false /* did_device_registry_change */,
-                                base::nullopt /* client_directive */));
-
-  EXPECT_TRUE(scheduler()->IsWaitingForEnrollmentResult());
-}
-
 }  // namespace device_sync
 
 }  // namespace chromeos

chromeos/services/device_sync/fake_cryptauth_scheduler.cc

@@ -21,6 +21,7 @@ FakeCryptAuthScheduler::~FakeCryptAuthScheduler() = default;
 void FakeCryptAuthScheduler::RequestEnrollment(
     const cryptauthv2::ClientMetadata::InvocationReason& invocation_reason,
     const base::Optional<std::string>& session_id) {
+  DCHECK(HasEnrollmentSchedulingStarted());
   is_waiting_for_enrollment_result_ = true;
 
   cryptauthv2::ClientMetadata client_metadata;
@@ -36,6 +37,7 @@ void FakeCryptAuthScheduler::RequestEnrollment(
 void FakeCryptAuthScheduler::RequestDeviceSync(
     const cryptauthv2::ClientMetadata::InvocationReason& invocation_reason,
     const base::Optional<std::string>& session_id) {
+  DCHECK(HasDeviceSyncSchedulingStarted());
   is_waiting_for_device_sync_result_ = true;
 
   cryptauthv2::ClientMetadata client_metadata;