Sync with CrOS error codes.

Add to ErrorCode and metrics::DownloadErrorCode:

- kInternalLibCurlError
- kUnresolvedHostError
- kUnresolvedHostRecovered

Test: builds
Change-Id: Ibe11c02137860aed583b00b7e05b089ef84edb03
diff --git a/common/error_code.h b/common/error_code.h
index 252cc42..3dd7402 100644
--- a/common/error_code.h
+++ b/common/error_code.h
@@ -80,6 +80,9 @@
   kRollbackNotPossible = 54,
   kFirstActiveOmahaPingSentPersistenceError = 55,
   kVerityCalculationError = 56,
+  kInternalLibCurlError = 57,
+  kUnresolvedHostError = 58,
+  kUnresolvedHostRecovered = 59,
 
   // VERY IMPORTANT! When adding new error codes:
   //
diff --git a/common/error_code_utils.cc b/common/error_code_utils.cc
index b0bbbd4..5bcbaa4 100644
--- a/common/error_code_utils.cc
+++ b/common/error_code_utils.cc
@@ -161,6 +161,12 @@
       return "ErrorCode::kFirstActiveOmahaPingSentPersistenceError";
     case ErrorCode::kVerityCalculationError:
       return "ErrorCode::kVerityCalculationError";
+    case ErrorCode::kInternalLibCurlError:
+      return "ErrorCode::kInternalLibCurlError";
+    case ErrorCode::kUnresolvedHostError:
+      return "ErrorCode::kUnresolvedHostError";
+    case ErrorCode::kUnresolvedHostRecovered:
+      return "ErrorCode::kUnresolvedHostRecovered";
       // Don't add a default case to let the compiler warn about newly added
       // error codes which should be added here.
   }