If you open 6 - 8 windows on a minnie and toggle overview mode continuously the UI will hang.

At some point TileManager hits the task limit and has more tiles to schedule. Later when all scheduled tiles finish, the only tiles left are solid color tiles so CheckIfMoreTilesNeedToBePrepared returns after processing these. NotifyReadyToDraw isn't scheduled in the previous IsReadyToDraw because one of the solid color tiles is required for draw.

This can be fixed in a couple of ways:
1. Do not early out on task limit in AssignGpuMemoryToTiles so that all solid color tiles are processed.
2. If there are no tiles to process in CheckIfMoreTilesNeedToBePrepared but there were ready to activate/draw solid color tiles, schedule ready to activate/draw checks.

It's possible the same issue is responsible for missing ready to activate signal causing renderer hangs - issue 622080
 
Log from device:
TileManager::AssignGpuMemory over task limit
TileManager::AssignGpuMemory skipping tile { tile: { id: 244769, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244808, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244770, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244809, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244771, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244810, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244775, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244776, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244777, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244778, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory skipping tile { tile: { id: 244779, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AreRequiredTilesReadyToDraw all pass
TileManager::AreRequiredTilesReadyToDraw process tile { tile: { id: 244775, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory process tile { tile: { id: 244775, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory solid color
TileManager::AssignGpuMemory process tile { tile: { id: 244776, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory solid color
TileManager::AssignGpuMemory process tile { tile: { id: 244777, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory solid color
TileManager::AssignGpuMemory process tile { tile: { id: 244778, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory solid color
TileManager::AssignGpuMemory process tile { tile: { id: 244779, rfa: 0, rfd: 1 }, priority: { bin: 0, dtv: 0.000000 }, occluded: 0, img_only: 0 }
TileManager::AssignGpuMemory solid color
< Compositor hangs here - begin frames keep coming in but no ready to draw signal >