[tor-bugs] #19193 [Applications/Tor Browser]: AudioContext, HTMLMediaElement, and MediaStream provide currentTime to content scripts

[Tor Bug Tracker & Wiki]

#19193: AudioContext, HTMLMediaElement, and MediaStream provide currentTime to
content scripts
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     Reporter:  arthuredelstein           |      Owner:  tbb-team
         Type:  defect                    |     Status:  new
     Priority:  Medium                    |  Milestone:
    Component:  Applications/Tor Browser  |    Version:
     Severity:  Normal                    |   Keywords:
Actual Points:                            |  TorBrowserTeam201605
       Points:                            |  Parent ID:
      Sponsor:                            |   Reviewer:
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 The worst offender is probably AudioContext, where you can get
 the current time thus:

 {{{
 var audioContext = new AudioContext();
 audioContext.currentTime;
 }}}

 Similarly, HTMLVideoElement.currentTime, HTMLAudioElement.currentTime, and
 CanvasCaptureMediaStream.currentTime can be used as a time source with
 resolution better than 10 ms.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19193>
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