Copy resume callbacks list prior to making callbacks

- Starting a deferred activity can trigger a new callback to be added
  to the list while we are iterating it

Bug: 136613192
Change-Id: I6690ab0695bb73f11bf343fb41e9fc86b4afec1b
Merged-In: I6690ab0695bb73f11bf343fb41e9fc86b4afec1b
(cherry picked from commit 940b0ac0)
(cherry picked from commit a8971c14)