Summary: Some more minor cleanups that don't (well, barely) affect semantics. - Fix singleton management in multi-threaded environments. - Remove double assignment. - Make all things final where they can be. - Use ugly Hungarian notation. - Weaken some types. Reviewed By: mweststrate Differential Revision: D19471227 fbshipit-source-id: 18833c3fe940f51b8d4cb3948a63387b8cd9316c