Roll src/third_party/pdfium 5e97d0125fd9..42424bf2eab6 (4 commits)

https://pdfium.googlesource.com/pdfium.git/+log/5e97d0125fd9..42424bf2eab6

git log 5e97d0125fd9..42424bf2eab6 --date=short --no-merges --format='%ad %ae %s'
2019-08-13 tsepez@chromium.org Remove SystemFontInfoIface::MapFontByUnicode().
2019-08-13 tsepez@chromium.org Remove knowlege of whether XFA is present from pwl/ window layer
2019-08-13 thestig@chromium.org Do CPDF_CMap loading in the constructors.
2019-08-13 thestig@chromium.org Remove CXFA_Document::HasFlag() and SetFlag().

Created with:
  gclient setdep -r src/third_party/pdfium@42424bf2eab6

The AutoRoll server is located here: https://autoroll.skia.org/r/pdfium-autoroll

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

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.


TBR=pdfium-deps-rolls@chromium.org

Bug: None
Change-Id: Icdf518953b0e68a0b12963767fa8ae12de1f1f35
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1752782Reviewed-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@{#686594}

DEPS

@@ -165,7 +165,7 @@ 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': '5e97d0125fd968b043ce7e39e7a6409595343234',
+  'pdfium_revision': '42424bf2eab6c676036939a1503defde66e0a4eb',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.