Add littledan/dehrenberg to docs/user_handle_mapping.md

Review URL: https://codereview.chromium.org/1884053002

Cr-Commit-Position: refs/heads/master@{#387450}
diff --git a/docs/user_handle_mapping.md b/docs/user_handle_mapping.md
index e3559a0..f0c7ad7 100644
--- a/docs/user_handle_mapping.md
+++ b/docs/user_handle_mapping.md
@@ -58,6 +58,7 @@
 | kuchhal           | kuchhal         | rahulk          |
 | levin             | dave\_levin     | levin           |
 | lfg               | lfg\_           | lfg             |
+| littledan         | littledan       | dehrenberg      |
 | luken             | luken_chromium  | luken           |
 | mark              | markmentovai    | mmentovai       |
 | mattm             | mattm\_c, mattm\_g | mattm           |