Roll src/third_party/pdfium f793e3abc4ec..3c04fb3a9464 (3 commits)

https://pdfium.googlesource.com/pdfium.git/+log/f793e3abc4ec..3c04fb3a9464

git log f793e3abc4ec..3c04fb3a9464 --date=short --first-parent --format='%ad %ae %s'
2020-01-09 tsepez@chromium.org Cover FPDF_GetDefaultTTFMap() from embedder tests.
2020-01-09 tsepez@chromium.org Watch CFXA_FFWidgets across more On* methods.
2020-01-09 tsepez@chromium.org Ensure CFWL_Widget::m_pTextOut is initialized.

Created with:
  gclient setdep -r src/third_party/pdfium@3c04fb3a9464

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: I18e4257ed9a16265973dfb124855b024adb0903c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1993881Reviewed-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@{#729928}

DEPS

@@ -201,7 +201,7 @@ 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': 'f793e3abc4ecaea52b9f1e960df3505233e466d6',
+  'pdfium_revision': '3c04fb3a9464c99334c4b71eb48288da8f56a1cf',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.