Weak references save / restore involves multiple interface indirection
and cause material latency overhead when there are lots of dirents, each
containing a weak reference map. The nil entries in the map should also
be purged.
PiperOrigin-RevId: 210593727
Change-Id: Ied6f4c3c0726fcc53a24b983d9b3a79121b6b758
Ian Gudger
Zhaozhong Ni
Nicolas Lacasse
Googler