Summary:
Fabric has a feature that preallocates views before mounting even need them. We never tested the impact of this feature thought. This diff adds a way to enable/disable it and run an experiment.
Changelog: [Internal] Fabric-specific internal change.
Reviewed By: JoshuaGross
Differential Revision: D24355612
fbshipit-source-id: fefd653e57232044cd7b28b160e12a4ef85dbb8b