SkPDF: centralize procsets to remove duplication

Change-Id: I32dbb88c5c28a5c44f922826516eeb2221ae4b38
Reviewed-on: https://skia-review.googlesource.com/c/160384
Auto-Submit: Hal Canary <halcanary@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
3 files changed