Roll src/third_party/pdfium/ 77417ec9e..3f753f20e (3 commits)

https://pdfium.googlesource.com/pdfium.git/+log/77417ec9e131..3f753f20e9c5

$ git log 77417ec9e..3f753f20e --date=short --no-merges --format='%ad %ae %s'
2017-07-20 rharrison Change length calculation in CFX_StringCTemplate constructor
2017-07-20 art-snake Use enum for pdf object type
2017-07-20 npm Upgrade LibTIFF to 4.0.8

Created with:
  roll-dep src/third_party/pdfium


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

Change-Id: Iedf571faf2d80398ea6a3fb126fc57d53d8d0446
Reviewed-on: https://chromium-review.googlesource.com/580352
Reviewed-by: <pdfium-deps-roller@chromium.org>
Commit-Queue: <pdfium-deps-roller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488450}

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': '77417ec9e1312a75407f8ab46dd46f777a1742f1',
+  'pdfium_revision': '3f753f20e9c51f7170a616a355b3f9578505c0ee',
   # 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.