The chromium callers were updated in https://crrev.com/c/868287,
while the pdfium callers were updated in
https://pdfium-review.googlesource.com/c/pdfium/+/23058.

As a precaution to avoid a repeat of https://crbug.com/803330,
I've manually built pdfium, along with the additional gn flag
"pdf_enable_xfa = true".

Bug: v8:7269, v8:7282
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I5b8cfb629c2b78627447c940a133d75d7ef7c6e9
Reviewed-on: https://chromium-review.googlesource.com/875252Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50821}