Roll PDFium e4ac336..28de044

https://pdfium.googlesource.com/pdfium.git/+log/e4ac336..28de044

TBR=thestig@chromium.org
BUG=587227

Review URL: https://codereview.chromium.org/1728813002

Cr-Commit-Position: refs/heads/master@{#377136}