Roll src/third_party/pdfium/ 4e4147ecc..2dca1cbf5 (2 commits)

https://pdfium.googlesource.com/pdfium.git/+log/4e4147eccd25..2dca1cbf5956

$ git log 4e4147ecc..2dca1cbf5 --date=short --no-merges --format='%ad %ae %s'
2018-04-23 dsinclair Cleanup CFX_XMLParser initialization
2018-04-23 rharrison Pre-allocate more string buffers in barcode code

Created with:
  roll-dep src/third_party/pdfium
BUG=chromium:834630


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: If2eb29c9bd23bb4d07f64549fcf72626d3c6bff6
Reviewed-on: https://chromium-review.googlesource.com/1025226
Commit-Queue: pdfium-chromium-autoroll <pdfium-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Reviewed-by: pdfium-chromium-autoroll <pdfium-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#552983}

DEPS

@@ -114,7 +114,7 @@ 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': '4e4147eccd25e66a5c61712121c30c8d5f2ba56c',
+  'pdfium_revision': '2dca1cbf595618e06547a2c464d82c47b6acace6',
   # 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.