basesink: merge preroll functions
basesink: merge preroll functions

Inline a function that is only called from one place to make things a little
easier to follow.

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