Separate callbacks for dismiss start and end

Bug: 219790596
Test: manual
Change-Id: I1ab46134b994cebff606345af62bf70f79a92e3f
Merged-In: I1ab46134b994cebff606345af62bf70f79a92e3f
(cherry picked from commit 11db9a363ba7f6f41b03c44619425b95204bce41)
4 files changed