Rewrite most of the scopers in //base/mac to use ScopedTypeRef or ScopedGeneric.

This removes a lot of duplicated code in favor of using type aliases and
minimal Traits structs.

R=mark@chromium.org

Review URL: https://codereview.chromium.org/1551943002 .

Cr-Commit-Position: refs/heads/master@{#367322}
21 files changed