Roll src/third_party/pdfium/ ffdfbb9ec..e7fb8eb3e (1 commit).

https://pdfium.googlesource.com/pdfium.git/+log/ffdfbb9ec274..e7fb8eb3e9f2

$ git log ffdfbb9ec..e7fb8eb3e --date=short --no-merges --format='%ad %ae %s'
2017-01-11 npm Prevent undefined shift in putagreytile

BUG=655008

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/2624133005
Cr-Commit-Position: refs/heads/master@{#443258}

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': 'ffdfbb9ec274785e01dbdb64e9eef624fc1fb2e4',
+  'pdfium_revision': 'e7fb8eb3e9f220a5f0c852f0238ab8d536a8bc9d',
   # 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.