Built-in PDF plugin problems after opening 18+ PDF tabs

Description of the issue:

I have encountered the issue that after opening 18+ pdfs in Brave, the pdf viewer stops loading new documents. Specifically, when I try to open a new pdf by clicking a link, I get the same viewer screen but with the message “Couldn’t load a plugin.” instead of the pdf.

Moreover, it also triggers an issue with printing from the web interface: when I try to print a Google Doc, the printing preview appears but with the message “Brave cannot show the print preview when the built-in PDF viewer is missing.”, instead of the document preview. The Print button is greyed out, the destination field is constantly loading (the circling loading image) and the only active option is to cancel. The issue with the printing preview seems to appear at 3+ pdfs after the issue with pdf loading (you would still need try to open a couple more pdfs and keep the tabs with the error message).

The issues persist even when these pdfs are split among several browser windows. I have tried disabling all the plugins and also opening a pdf in a private window but nothing helps.

How can this issue be reproduced?

Unfortunately, the issue is not exactly deterministic so I have not been able to come with a step-by-step reproduction guide. The approximate steps are

  1. Open 18+ pdfs in a separate tab each. The pdfs have to be located on different servers / hosts (If I go to some conference page and try to open as many pdfs as possible there, it works fine). Also, some servers do not affect the count, e.g., I could open more pdfs from arxiv.org even when it would not work for other websites.
  2. At some point, you start getting the error message from the viewer plugin that it couldn’t be loaded. The issue with the print preview also appears.

Expected result:
Not getting the plugin error message.

Brave Version( check About Brave):
Version 1.2.43 Chromium: 79.0.3945.130 (Official Build) (64-bit)