Roll src/third_party/pdfium/ 99acb1c81..1ff9b7ffa (5 commits)

https://pdfium.googlesource.com/pdfium.git/+log/99acb1c816dc..1ff9b7ffa653

$ git log 99acb1c81..1ff9b7ffa --date=short --no-merges --format='%ad %ae %s'
2017-11-28 dsinclair Remove CollectionSize from fpdfppo.
2017-11-28 dsinclair Remove CollectionSize from fpdf_flatten.
2017-11-28 dsinclair Remove CollectionSize from string_view_template
2017-11-28 dsinclair Remove CollectionSize from JBig2_Context
2017-11-28 rharrison Convert from character stream to visible text indices in GetText

Created with:
  roll-dep src/third_party/pdfium
BUG=788103,788220


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

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=dsinclair@chromium.org

Change-Id: Iefdff68f09558ee706d0702bf47b8241a7141f4c
Reviewed-on: https://chromium-review.googlesource.com/794026
Reviewed-by: <pdfium-deps-roller@chromium.org>
Commit-Queue: <pdfium-deps-roller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519878}

DEPS

@@ -98,7 +98,7 @@ 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': '99acb1c816dc88dbda5d03ef28dbdaa928f7e22a',
+  'pdfium_revision': '1ff9b7ffa653de1d25c5e013d731054815b13e86',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling openmax_dl
   # and whatever else without interference from each other.