Remove uses of implicit conversion of ScopedTypeRef in /media

Implicit unwrapping of a scoper to its underlying pointer is dangerous
and that capability is being removed. This converts uses of implicit
conversion to be explicit in preparation for its removal, and performs
other cleanup and modernization.

Bug: 1495439
Low-Coverage-Reason: LARGE_SCALE_REFACTOR Switching from implicit to explicit
Change-Id: I9d20564c781493f05f7e91b0bef9f0037450d4bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4981008
Commit-Queue: Mark Foltz <mfoltz@chromium.org>
Reviewed-by: Mark Foltz <mfoltz@chromium.org>
Reviewed-by: Henrik Boström <hbos@chromium.org>
Auto-Submit: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1216265}