Add ErrorCode::kDeviceCorrupted.

This error code indicates the device is corrupted in a way
that it can no longer receive any future updates. Specifically, if a
device encounters a merge error, there is no way we can recover that
device.

Test: pass
Bug: 138808328

Change-Id: Idbd9d1bc5bc02bbba157f17f31b2c5ace839243c
diff --git a/update_manager/chromeos_policy.cc b/update_manager/chromeos_policy.cc
index 22e5094..1fa8636 100644
--- a/update_manager/chromeos_policy.cc
+++ b/update_manager/chromeos_policy.cc
@@ -153,6 +153,7 @@
     case ErrorCode::kUnresolvedHostError:
     case ErrorCode::kUnresolvedHostRecovered:
     case ErrorCode::kNotEnoughSpace:
+    case ErrorCode::kDeviceCorrupted:
       LOG(INFO) << "Not changing URL index or failure count due to error "
                 << chromeos_update_engine::utils::ErrorCodeToString(err_code)
                 << " (" << static_cast<int>(err_code) << ")";