basesink: more cleanups
basesink: more cleanups

Don't pass around the object type, we can find that very efficiently from the
object itself now.

ensonic/gstreamer,collects/gstreamer,jpxiong/gstreamer,mparis/gstreamer,jpakkane/gstreamer,lovebug356/gstreamer,cfoch/gstreamer,Lachann/gstreamer,krichter722/gstreamer,justinjoy/gstreamer,cfoch/gstreamer,surround-io/gstreamer,StreamUtils/gstreamer,jpakkane/gstreamer,collects/gstreamer,ensonic/gstreamer,jpxiong/gstreamer,centricular/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,krichter722/gstreamer,mparis/gstreamer,krieger-od/gstreamer,Lachann/gstreamer,ensonic/gstreamer,shelsonjava/gstreamer,centricular/gstreamer,cablelabs/gstreamer,lubosz/gstreamer,lubosz/gstreamer,ensonic/gstreamer,krieger-od/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,krieger-od/gstreamer,mparis/gstreamer,lubosz/gstreamer,jpxiong/gstreamer,surround-io/gstreamer,StreamUtils/gstreamer,jpakkane/gstreamer,cablelabs/gstreamer,lubosz/gstreamer,shelsonjava/gstreamer,shelsonjava/gstreamer,collects/gstreamer,lovebug356/gstreamer,krichter722/gstreamer,centricular/gstreamer,jpakkane/gstreamer,jpakkane/gstreamer,mparis/gstreamer,justinjoy/gstreamer,krieger-od/gstreamer,surround-io/gstreamer,krichter722/gstreamer,centricular/gstreamer,lovebug356/gstreamer,collects/gstreamer,StreamUtils/gstreamer,cfoch/gstreamer,lovebug356/gstreamer,mparis/gstreamer,cablelabs/gstreamer,justinjoy/gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,ensonic/gstreamer,lovebug356/gstreamer,surround-io/gstreamer,justinjoy/gstreamer,justinjoy/gstreamer,cfoch/gstreamer,jpxiong/gstreamer,krieger-od/gstreamer,Lachann/gstreamer,cfoch/gstreamer,shelsonjava/gstreamer,collects/gstreamer,lubosz/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,cablelabs/gstreamer,surround-io/gstreamer,Lachann/gstreamer