[tor-bugs] #7130 [Firefox Patch Issues]: Canvas image data is blocked from chrome callers

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#7130: Canvas image data is blocked from chrome callers
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 Reporter:  mikeperry             |          Owner:  mikeperry
     Type:  defect                |         Status:  new      
 Priority:  normal                |      Milestone:           
Component:  Firefox Patch Issues  |        Version:           
 Keywords:                        |         Parent:           
   Points:                        |   Actualpoints:           
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 Something about how Chrome callers (especially NoScript) can create
 canvases can leave them without any window or context for their owner
 document for ThirdPartyUtil::GetFirstPartyURI(). In #7128, we just hacked
 the GetFirstPartyURI call to return failure, which in turn should block
 permissions to the canvas.

 However, the ideal solution is probably to either check IsChrome() or
 otherwise find some way to exempt NoScript.

 It's possible that we break NoScript's ClearClick protections because of
 this issue.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/7130>
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