Removed redundant `get()` call on a smart pointer.
Removed redundant `get()` call on a smart pointer.

Registrar had the type `Owned<MockRegistry>` so this call was
indeed redundant.

Review: https://reviews.apache.org/r/64383/

andschwa/mesos,asamerh4/mesos,chhsia0/mesos,reneploetz/mesos,gsantovena/mesos,reneploetz/mesos,reneploetz/mesos,Gilbert88/mesos,jpeach/mesos,dforsyth/mesos,Gilbert88/mesos,dforsyth/mesos,asamerh4/mesos,jpeach/mesos,gsantovena/mesos,abudnik/mesos,kaysoky/mesos,asamerh4/mesos,dforsyth/mesos,kaysoky/mesos,jpeach/mesos,kaysoky/mesos,andschwa/mesos,Gilbert88/mesos,andschwa/mesos,reneploetz/mesos,chhsia0/mesos,gsantovena/mesos,kaysoky/mesos,chhsia0/mesos,andschwa/mesos,asamerh4/mesos,kaysoky/mesos,chhsia0/mesos,andschwa/mesos,gsantovena/mesos,jpeach/mesos,asamerh4/mesos,abudnik/mesos,Gilbert88/mesos,gsantovena/mesos,gsantovena/mesos,dforsyth/mesos,reneploetz/mesos,dforsyth/mesos,reneploetz/mesos,jpeach/mesos,kaysoky/mesos,abudnik/mesos,Gilbert88/mesos,abudnik/mesos,abudnik/mesos,dforsyth/mesos,jpeach/mesos,andschwa/mesos,chhsia0/mesos,abudnik/mesos,asamerh4/mesos,reneploetz/mesos,chhsia0/mesos,asamerh4/mesos,dforsyth/mesos,Gilbert88/mesos,andschwa/mesos,kaysoky/mesos,gsantovena/mesos,chhsia0/mesos,Gilbert88/mesos,abudnik/mesos,jpeach/mesos