SyncFS: -1 GDataErrorCode should be handled gracefully

chrome/browser/sync_file_system/drive_file_sync_util.cc

Index: chrome/browser/sync_file_system/drive_file_sync_util.cc
diff --git a/chrome/browser/sync_file_system/drive_file_sync_util.cc b/chrome/browser/sync_file_system/drive_file_sync_util.cc
index 333de0d9342f094629e53df3431762d6c6031c23..76de67437261348ac50c722ffc05957dfd7f9d95 100644
--- a/chrome/browser/sync_file_system/drive_file_sync_util.cc
+++ b/chrome/browser/sync_file_system/drive_file_sync_util.cc
@@ -56,7 +56,15 @@ SyncStatusCode GDataErrorCodeToSyncStatusCode(
     case google_apis::GDATA_NO_SPACE:
       return SYNC_FILE_ERROR_NO_SPACE;
   }
-  NOTREACHED();
+
+  // There's a case where DriveService layer returns GDataErrorCode==-1
+  // when network is unavailable. (http://crbug.com/223042)
+  // TODO(kinuko,nhiroki): We should identify from where this undefined error
+  // code is coming.
+  if (error == -1)
+    return SYNC_STATUS_NETWORK_ERROR;
+
+  LOG(WARNING) << "Got unexpected error: " << error;
   return SYNC_STATUS_FAILED;
 }