DM: excercise other SkPDF raster dpis

Change-Id: Ia50661a8391da526d509adbe2d7203866c140b1c
Reviewed-on: https://skia-review.googlesource.com/25321
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
3 files changed