Various Scavenger fixes for smaller issues that accumulated over the
last years.

Bug: chromium:738865
Change-Id: I7573e438eba030944b99c65807944c662526a171
Reviewed-on: https://chromium-review.googlesource.com/567190
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46578}