Potential fix for end callback not being run in 3-button

- Context: With shell transitions, the launch of a new task is merged
  into the same recents transition that is running, which means that it
  does not run as its own independent transition (this probably needs
  to be addressed in the transitions level somehow)
- Given the above, if there is somehow no running task id, then we still
  need to rely on the next task appeared to trigger the flush of the
  callback list (since the animation will not run to flush that callback)

Bug: b/255851262
Test: Manually simulate getRunningTaskViewId() == 1 and verify

Change-Id: I778f22fa59cb1620781f7aa442d244793352d74e
Signed-off-by: Winson Chung <winsonc@google.com>
1 file changed