This will make it much less likely for application developers to not realize the object is reference counted. It also fixes a bug in the Java PeerConnection binding, by allowing a reference to be transferred in the OnRemoveStream call via std::move. BUG=webrtc:5128 R=pthatcher@webrtc.org, tkchin@webrtc.org Review URL: https://codereview.webrtc.org/1972793003 . Cr-Commit-Position: refs/heads/master@{#12976}