[tor-bugs] #13027 [Tor Browser]: Make WebWorkers use spoofed navigator.* useragent values

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#13027: Make WebWorkers use spoofed navigator.* useragent values
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     Reporter:           |      Owner:  tbb-team
  mikeperry              |     Status:  new
         Type:  defect   |  Milestone:
     Priority:  major    |    Version:
    Component:  Tor      |   Keywords:  ff31-esr, tbb-easy, tbb-
  Browser                |  fingerprinting, TorBrowserTeam201409Easy
   Resolution:           |  Parent ID:
Actual Points:           |
       Points:           |
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Comment (by gacar):

 It seems worker calls doesn't listen to prefs because they are treated as
 chrome calls.

 I debugged `NS_GetNavigator*` methods that are used to
 [https://mxr.mozilla.org/mozilla-
 esr24/source/dom/workers/RuntimeService.cpp#1170 initialize
 WorkerNavigator] and confirmed that `IsCallerChrome()` returns true for
 worker scripts (check esp. [https://mxr.mozilla.org/mozilla-
 esr24/source/dom/base/Navigator.cpp#1673 1], [https://mxr.mozilla.org
 /mozilla-esr24/source/dom/base/Navigator.cpp#1717 2]).

 This also explains why useragent matches between worker and global
 context: there's no
 `IsCallerChrome()` check in [https://mxr.mozilla.org/mozilla-
 esr24/source/netwerk/protocol/http/nsHttpHandler.cpp#548
 nsHttpHandler.cpp] where useragent value comes from.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13027#comment:6>
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