(In reply to Kris Maglione [:kmag] from comment #25) > Has the test been updated to use the new snapshot API? Using a canvas to draw a cross-process iframe from a child process is never going to work, so even if it's loaded, it will still appear blank in that case. Yes, that was done about 2 weeks ago via bug 1559592. The tests can be made work when you add a sleep right after navigation, as such I'm 99% it's related to this bug. Note that those tests make use of data URLs, in case that this makes a difference.
Bug 1559841 Comment 26 Edit History
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(In reply to Kris Maglione [:kmag] from comment #25) > Has the test been updated to use the new snapshot API? Using a canvas to draw a cross-process iframe from a child process is never going to work, so even if it's loaded, it will still appear blank in that case. Yes, that was done about 2 weeks ago via bug 1559592. The tests can be made work when you add a sleep right after navigation, as such I'm 99% sure it's related to this bug. Note that those tests make use of data URLs, in case that this makes a difference.