nlecomposition: Start task and initialize the stack after chaining up to...
nlecomposition: Start task and initialize the stack after chaining up to parent's change state function Otherwise we could set the state of the children to PAUSED already (i.e. start dataflow) from the composition's task, while the composition itself is currently chaining up to the parent class' change state function and did not activate the pads yet. This causes buffers and events to be discarded, and everything to stop with a not-negotiated error. https://bugzilla.gnome.org/show_bug.cgi?id=774480