Roll src/third_party/pdfium/ cb6c8d4ec..24d779283 (6 commits)

https://pdfium.googlesource.com/pdfium.git/+log/cb6c8d4ec478..24d779283af8

$ git log cb6c8d4ec..24d779283 --date=short --no-merges --format='%ad %ae %s'
2018-01-04 rharrison Convert CXFA_Node::GetChild to take a size_t for the index
2018-01-03 npm Remove unneeded vector implementations from cpwl_edit_impl
2018-01-04 rharrison Convert usages of pdfium::Optional to Optional
2018-01-02 dsinclair Remove allocations from JS test
2018-01-04 rharrison Make indices for CXFA_List be size_t instead of int32_t
2018-01-04 hnakashima Open FPDFDest_GetView API.

Created with:
  roll-dep src/third_party/pdfium


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: I8a0ac1395a018d2025616b47adbb34f7359c8fff
Reviewed-on: https://chromium-review.googlesource.com/850996
Reviewed-by: <pdfium-deps-roller@chromium.org>
Commit-Queue: <pdfium-deps-roller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#527153}

DEPS

@@ -102,7 +102,7 @@ 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': 'cb6c8d4ec4781c7db8448f2b4d9a8af879cf014e',
+  'pdfium_revision': '24d779283af803077d8377fbdc49d9d07da335e7',
   # 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.