bb956bd028
Add a custom drawable class that provides a hook to the caller to control a crossfade animation between two drawables. This will be helpful going forward to sync up all the animations to the controller. Note that this CL only adds the class and does not replace the current implementation. Bug: 114136250 Test: Builds Change-Id: I3cc6be79cb2ca5d64c8cc2945ff7f2ebd49632b6