[tor-bugs] #17046 [Tor Browser]: Event.timeStamp reveals startup time

[Tor Bug Tracker & Wiki]

#17046: Event.timeStamp reveals startup time
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     Reporter:           |      Owner:  tbb-team
  arthuredelstein        |     Status:  needs_information
         Type:  defect   |  Milestone:
     Priority:  normal   |    Version:
    Component:  Tor      |   Keywords:  tbb-linkability,
  Browser                |  TorBrowserTeam201509R
   Resolution:           |  Parent ID:
Actual Points:           |
       Points:           |
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Comment (by arthuredelstein):

 Replying to [comment:7 mikeperry]:
 > One thing we should verify is that flipping this pref does indeed
 normalize the three timestamps for events for Windows, Linux, and Mac. It
 sounds like there is some risk that MacOS may not be normalized yet,
 depending on what the state of this pref was when FF38 was branched?

 I have now tested
 https://arthuredelstein.github.io/tordemos/event-timestamp.html
 with TBB 5.0.2 on Windows, Ubuntu, and OS X.

 On all platforms, with the pref disabled, I get results like:
 {{{
 evt.timeStamp: 208597200
 new Event('').timeStamp: 1442351957753400
 performance.now(): 151700
 }}}
 If I enable the pref, I get:
 {{{
 evt.timeStamp: 204900
 new Event('').timeStamp: 204900
 performance.now(): 204900
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17046#comment:8>
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