Roll PDFium 8b45eb1..3cbb6fb

      https://pdfium.googlesource.com/pdfium.git/+log/8b45eb1..3cbb6fb

BUG=613160
TBR=thestig@chromium.org

Review-Url: https://codereview.chromium.org/1999153002
Cr-Commit-Position: refs/heads/master@{#395117}