Roll PDFium d8cc503..6f10254

https://pdfium.googlesource.com/pdfium.git/+log/d8cc503..6f10254

BUG=630654
TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2190853004
Cr-Commit-Position: refs/heads/master@{#408419}