Roll src/third_party/pdfium/ 37b12ad87..72a22025e (1 commit).

https://pdfium.googlesource.com/pdfium.git/+log/37b12ad87319..72a22025ec44

$ git log 37b12ad87..72a22025e --date=short --no-merges --format='%ad %ae %s'
2016-12-14 tsepez Remove unused m_OtfFontData.

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/2575393002
Cr-Commit-Position: refs/heads/master@{#438777}

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': '37b12ad873198a9644f3de0d2eff001285e1ad42',
+  'pdfium_revision': '72a22025ec4402178cd0b27239bf77cf3a953949',
   # 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.