Make Pip usage of FrameCallbackScheduler an actual class Bug: 175330528 Test: Builds with new dynamic-animation library Change-Id: I1632bd87a0f02940317a38a87b074d303f80b8c7 Merged-In: I1632bd87a0f02940317a38a87b074d303f80b8c7 (cherry picked from commit c6c603078b9a32f00b205b23919faea47343f54d)