Rewrite reference field into const raw_ref<T>

No-Tree-Checks: true

Bug: 40268473
Change-Id: Iee194e1524d1bac3dcd9ed1ee407f1af2a062308
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5397781


Commit-Queue: Ali Hijazi <ahijazi@chromium.org>
Owners-Override: Ravjit Uppal <ravjit@google.com>
Commit-Queue: Ravjit Uppal <ravjit@chromium.org>
Reviewed-by: Elias Klim <elklm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1278877}