[Status Bar Refactor] 1/3: Move status bar window's animation controller into
a method inside StatusBarWindowController, rather than being in
StatusBar.java.

Test: Test steps in ag/14294127 (specifically, that the updated
animation in b/183229367#comment11 still occurs)
Bug: 204583449

Change-Id: Ib4e8a18250db0cabed490fe286e8944262cc4f9c
2 files changed