urisourebin: make sure output slot is being removed when no avaliable pending pad

Dear All.

I have an issue in urisourcebin.

Actually, I use dashdemux to playback for recorded file in our target environment (e.g TV). Our scenario does not have audio pad in adaptivedemux when trick play (e.g -2x).

When we change playback rate (-2x <-> 1x), playbin3 pipeline is stuck. Internally, output slot of urisourcebin's audio is not removed and not unlinked to decodebin3's audiosink when -2x. We expect that output slot is also removed when EOS is fired in case no available pending pad.

When custom-eos event is received on source_pad_event_probe and it is originated from demux_pad_events, this symptom is observed.

I am attaching the log and it is based 1.14.4. urisrcbin_ng.zip

Thanks.