[tor-bugs] #25214 [Applications/Tor Browser]: Canvas data extraction should be allowed when *local* pdf.js is invoked

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#25214: Canvas data extraction should be allowed when *local* pdf.js is invoked
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     Reporter:  cypherpunks               |      Owner:  tbb-team
         Type:  defect                    |     Status:  new
     Priority:  Medium                    |  Milestone:
    Component:  Applications/Tor Browser  |    Version:
     Severity:  Normal                    |   Keywords:
Actual Points:                            |  Parent ID:
       Points:                            |   Reviewer:
      Sponsor:                            |
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 How to reproduce the issue:

 (1) Go to the following URL:
 `https://web.archive.org/web/20180211235741/https://research.torproject.org/techreports
 /tbb-forensic-analysis-2013-06-28.pdf`

 (2) Click on the "Toggle Sidebar" button, as in here:

 [[Image(https://web.archive.org/web/20180212001338if_/https://prod-
 cdn.sumo.mozilla.net/uploads/images/2017-10-06-11-30-23-a9c34c.png)]]

 (3) The thumbnails are empty, and in the browser console: `Blocked
 https://web.archive.org/web/20180211235741if_/https://research.torproject.org/techreports
 /tbb-forensic-analysis-2013-06-28.pdf in page
 https://web.archive.org/web/20180211235741/https://research.torproject.org/techreports
 /tbb-forensic-analysis-2013-06-28.pdf from extracting canvas data.
 resource://pdf.js/web/viewer.js:3311.`

 Note that it's the local `resource://pdf.js/web/viewer.js` that is invoked
 and not some bundled pdf.js.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25214>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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