DO NOT MERGE - Slightly better encapsulation for the set of recent activities

Manual cherrypick from master since automated cherrypick had merge
conflicts.

Bug: 32101881
Test: Behavior is 100% covered by existing automated tests
Merged-In: Ibf2f5af268ec00abc8caa6232fb517b60545ad46
Change-Id: I04516c299ca00b2bfea731979af4aa918a056041