Roll src/third_party/pdfium 72f2915aa3b4..4a0f1a01ac8a (1 commits)

https://pdfium.googlesource.com/pdfium.git/+log/72f2915aa3b4..4a0f1a01ac8a

git log 72f2915aa3b4..4a0f1a01ac8a --date=short --first-parent --format='%ad %ae %s'
2020-02-11 maawas@microsoft.com Add a null check on return value of CPDF_StructTree::AddPageNode().

Created with:
  gclient setdep -r src/third_party/pdfium@4a0f1a01ac8a

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

Bug: None
Tbr: pdfium-deps-rolls@chromium.org
Change-Id: I2bf9ea862c7e9109d1b99c6154d47b2f19a5174c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2049666Reviewed-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@{#740212}

DEPS

@@ -191,7 +191,7 @@ 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': '72f2915aa3b45634c3a287d2cece5633c98a2920',
+  'pdfium_revision': '4a0f1a01ac8a9214c791e99baaf2ddbe914629da',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.