Use counter submission normally happens at document destruction. For
testing use counters, however, we need to have use counters updated in
telemetry at deterministic points. Therefore, we provide a method on
nsIDOMWindowUtils that forces use counters out to telemetry so we can
examine them.
imgFrame::SizeOfExcludingThis() measures heap and non-heap memory in a very
complex way. This patch simplifies it and removes gfxMemoryLocation in the
process. (gfxMemoryLocation::OUT_OF_PROCESS was unused.)
