Fix PDF reloading

[diracdeltas]

fix #12408

Test plan:

1. load any PDF
2. hit reload
3. it should reload the PDF instead of 'file not found'

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed. (Ask a Brave employee to help if you cannot access this document.)

Test Plan:

Reviewer Checklist:

• Request a security/privacy review as needed if one was not already requested.

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[bsclifton]

Verified broken before and fixed after using https://basicattentiontoken.org/BasicAttentionTokenWhitePaper-4.pdf

😄 👍

[bsclifton]

master f7d8df6
0.21.x 8dfe39f
0.20.x ec99115