Roll src/third_party/pdfium/ 469f6da24..8d94b6687 (1 commit).

https://pdfium.googlesource.com/pdfium.git/+log/469f6da247ff..8d94b6687f27

$ git log 469f6da24..8d94b6687 --date=short --no-merges --format='%ad %ae %s'
2017-01-06 rbpotter Revert postscript code removal.

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

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls

TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2612303005
Cr-Commit-Position: refs/heads/master@{#441987}

DEPS

@@ -64,7 +64,7 @@ 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': '469f6da247ffe77d0ae6089e5d93db0b0c0bb37e',
+  'pdfium_revision': '8d94b6687f27e1238f352939434704f75b330c1d',
   # 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.