Comment 7 for bug 1270245

most drivers return their buffers to us using ANativeWindow::queueBuffer(), which means, 'Here's the buffer back, its been rendered to"

there is another hook, cancelBuffer() that I've seen this class of drivers using, which means, "here's the buffer back, but its contents are indeterminate".

We currently treat those two hooks as the same (which is a TODO). I'll see if i can correlate the driver calling that hook to the times when the jump is seen.