Roll src/third_party/pdfium/ 9468639bc..8df023489 (6 commits).

https://pdfium.googlesource.com/pdfium.git/+log/9468639bc3c4..8df02348924f

$ git log 9468639bc..8df023489 --date=short --no-merges --format='%ad %ae %s'
2016-12-12 caryclark fix linux build
2016-12-12 weili Fix JBig2 decoding logic
2016-12-12 reed add flag for future Skia CL
2016-12-12 caryclark sync with latest skia api
2016-12-12 weili Fix dotted line drawing for GDI device driver
2016-12-12 reed add flag for SkClipOps

BUG=625848,539533

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/2566283004
Cr-Commit-Position: refs/heads/master@{#438033}

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': '9468639bc3c4620ba438e6715929019ca6930197',
+  'pdfium_revision': '8df02348924f66e14131aa378abc6c6ea7a352b6',
   # 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.