Roll src/third_party/pdfium/ e858aa4b7..a64cd6c86 (3 commits)

https://pdfium.googlesource.com/pdfium.git/+log/e858aa4b70db..a64cd6c86438

$ git log e858aa4b7..a64cd6c86 --date=short --no-merges --format='%ad %ae %s'
2017-06-01 dsinclair Remove unused Locale code
2017-05-31 tsepez Be less trusting of MaybeLocal<> return types from V8 To* methods.
2017-05-31 tsepez Missing one unowned_ptr in ccodec_progressivedecoder.h

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: I5724167552c757df9951af6619c894a637d578f1
Reviewed-on: https://chromium-review.googlesource.com/521204
Reviewed-by: <pdfium-deps-roller@chromium.org>
Commit-Queue: <pdfium-deps-roller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#476346}

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': 'e858aa4b70db7408bda1aed71827d9eee1dd98c5',
+  'pdfium_revision': 'a64cd6c86438636b031e1204057b27a8b9673296',
   # 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.