This method is called by the CreateClock method and should not be called directly by your code.
Notes to Implementers
Implementers of AnimationTimeline should override this method when it has a corresponding custom clock that should be used with the class. The overridden method should create and return a new instance of class that inherits from Clock.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)