Because passing ownership in raw pointers makes kittens cry. This also means we can ditch the Destroy functions and the protected destructors. (Well, almost. We need to keep the old CreateFilePlayer and DestroyFilePlayer around for a little while longer because of an external caller.) Review-Url: https://codereview.webrtc.org/2049683003 Cr-Commit-Position: refs/heads/master@{#13797}