Roll PDFium from c6c2cc49fa95 to 1f73c4f9367e (8 revisions)

https://pdfium.googlesource.com/pdfium.git/+log/c6c2cc49fa95..1f73c4f9367e

2020-07-29 nigi@chromium.org Enable FPDFEditEmbedderTest.EditOverExistingContent for Skia/SkiaPaths.
2020-07-28 thestig@chromium.org Add a pixel test for patterns that do not render.
2020-07-28 thestig@chromium.org Make CPDF_CIDFont::GetVertOrigin() return its results.
2020-07-28 nigi@chromium.org Enable FPDFAnnotEmbedderTest.FocusableAnnotRendering for Skia/SkiaPaths.
2020-07-28 nigi@chromium.org Enable FPDFParserDecodeEmbedderTest.Bug_455199 for Skia/SkiaPaths.
2020-07-28 thestig@chromium.org Fix a typo in FPDFSignatureEmbedderTest.GetByteRange.
2020-07-28 thestig@chromium.org Roll build/ 29bc35230..aae4f2e8c (68 commits)
2020-07-28 thestig@chromium.org Only run build/mac_toolchain.py on Mac.

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/+doc/master/autoroll/README.md

Bug: None
Tbr: pdfium-deps-rolls@chromium.org
Change-Id: I0c467251a0424c9e2cf73f40349e3dd8ecf12a4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2325556Reviewed-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@{#792590}

DEPS

@@ -215,7 +215,7 @@ 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': 'c6c2cc49fa957709e2ac1569041d4799feda9941',
+  'pdfium_revision': '1f73c4f9367e7355630754bfc2708eae8c160679',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.