[tbb-bugs] #27543 [Applications/Tor Browser]: QR code on http://web.whatsapp.com is only shortly visible in Tor Browser 8

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#27543: QR code on http://web.whatsapp.com is only shortly visible in Tor Browser 8
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 Reporter:  gk                                   |          Owner:  tbb-
                                                 |  team
     Type:  defect                               |         Status:
                                                 |  needs_review
 Priority:  Medium                               |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-8.0-issues, tbb-regression,      |  Actual Points:
  tbb-8.0.1-can, GeorgKoppen201809,              |
  TorBrowserTeam201809R                          |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
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Comment (by pospeselr):

 Replying to [comment:10 gk]:
 > Replying to [comment:9 pospeselr]:
 > > Replying to [comment:5 gk]:
 > > > Seems we need to flip
 `privacy.resistFingerprinting.autoDeclineNoUserInputCanvasPrompts` to
 `false` here as well, until the Mozilla bug gets fixed. I did that in
 `bug_27543` (https://gitweb.torproject.org/user/gk/tor-
 browser.git/commit/?h=bug_27543&id=ce60de442f949393b7f24acd153f82a57d78fe0e)
 in my public `tor-browser` repository. Please review.
 > >
 > > Unless I'm misundersanding things, it looks like you'll have to
 backport some code in CanvasUtils.cpp for that option to do anything (
 https://searchfox.org/mozilla-
 central/source/dom/canvas/CanvasUtils.cpp#146 ).
 >
 > No, https://bugzilla.mozilla.org/show_bug.cgi?id=1376865 has all we need
 already, I think (and made it into ESR 60).

 Ah my mistake, the pref getter is wrapped in the 'DOM_PREF' macro in
 /dom/base/DOMPrefsInternal.h which is used.  This patch looks good to me!

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27543#comment:11>
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