After https://bugs.chromium.org/p/chromium/issues/detail?id=730660 the tile resources are owned in ResourcePool. If they are exported and in flight to the display compositor, and we delete the ResourcePool to replace it, then those in flight resources are destroyed, which can cause a flash of black.

There's no strong reason to replace the ResourcePool anymore unless the ResourceProvider is changing (it has a pointer to that). So instead of deleting the ResourcePool when we don't delete the ResourceProvider (switching between gpu raster modes), we can just mark any resources in use atm as lost, so that they will not be reused.