SK_SUPPORT_LEGACY_DOCUMENT_FACTORY: clean up part 1/2

part 2 can follow after android patch lands.

Change-Id: If2a8135ac7384d84fd97d68933684ad8486d7471
Reviewed-on: https://skia-review.googlesource.com/156189
Auto-Submit: Hal Canary <halcanary@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
6 files changed