[fido] Fix Bugprone Clang Tidy Issues

This change fixes two small issues found by the recently proposed
bugprone clang-tidy checks [1].

[1] https://groups.google.com/a/chromium.org/g/cxx/c/hDDUlz1OMUw

Bug: None
Change-Id: I885cd1e019684f27a36265d9a11f65d554dc29f8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2582123
Reviewed-by: Nina Satragno <nsatragno@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835698}