Add manual roll support for PDFium to Chromium autorolls.
Add manual roll support for PDFium to Chromium autorolls.

Change-Id: I076c0654c0ab7e2f35133eedf183f41de70f265b
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/309237
Reviewed-by: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>
Commit-Queue: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot