base

Fix callback issue for AVD on UI thread

We have created AnimatorSet from XML, but it is assigned to the AVD only when
we start the animation due to theme-ing operations.

Given listeners can be added to AVD at any time, we have to cache them if
AnimatorSet is not setup yet.

b/26979225

Change-Id: I94315892de83f93a0205efe5e70dca0cd0f0a8e3