GitLab

The CL https://crrev.com/737514 fixes an issue with the PDF viewer
extension not loading if another extension injects an additional iframe
into the top-level HTML document for the PDF.

Not caught in the bug description is the fact that PostMessaging support
is also broken; that was discovered (and fixed) while writing the
accompanying test.

Bug: 1046795
Change-Id: I650518162e24e5d961e45b471bfb1518e9b7531c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2037343
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738361}