Roll src/third_party/pdfium/ 98151cab3..4d29e78fc (1 commit).

https://pdfium.googlesource.com/pdfium.git/+log/98151cab3d24..4d29e78fc802

$ git log 98151cab3..4d29e78fc --date=short --no-merges --format='%ad %ae %s'
2016-10-04 dsinclair Rename fpdfsdk/fpdfxfa files to match contents

TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2389983004
Cr-Commit-Position: refs/heads/master@{#422998}

DEPS

@@ -63,7 +63,7 @@ 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': '98151cab3d24c021597d1fb075437675a3db7e12',
+  'pdfium_revision': '4d29e78fc80285d222f2bad916354e3db970d0cc',
   # 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.