Cassie Wang a836fdcd45 Make ImplInstanceManager a singleton
This moves the whole class into a singleton style for consistency.

Bug: 178730366
Test: presubmit
Change-Id: Idbba534fa81e80fcd865ebc056dd8d24a301e691
2021-01-28 19:45:30 -08:00
..
2021-01-21 21:16:04 -08:00
2021-01-21 21:16:04 -08:00