Roll src/third_party/pdfium 0c0b073aed22..c6642beb8c78 (3 commits)

https://pdfium.googlesource.com/pdfium.git/+log/0c0b073aed22..c6642beb8c78

git log 0c0b073aed22..c6642beb8c78 --date=short --no-merges --format='%ad %ae %s'
2019-09-17 thestig@chromium.org Correctly draw text with pattern.
2019-09-17 thestig@chromium.org Test a different clip path in bug_632.in.
2019-09-17 thestig@chromium.org Simplify bug_632.in pixel test.

Created with:
  gclient setdep -r src/third_party/pdfium@c6642beb8c78

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/pdfium-autoroll
Please CC pdfium-deps-rolls@chromium.org on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

TBR=pdfium-deps-rolls@chromium.org

Bug: None
Change-Id: I9b9270258b9d6165083556e79f1535a65ba7c74c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1808232Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#697101}

DEPS

@@ -182,7 +182,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.
-  'pdfium_revision': '0c0b073aed22ab5836a4f46b72d631048c485d12',
+  'pdfium_revision': 'c6642beb8c78df9a7a85c2c431cde184a7e76ee5',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.