gfe-relnote: (n/a) comments only
gfe-relnote: (n/a) comments only

Add comments in QuicVersionManager detailing the usage of private flag members.

PiperOrigin-RevId: 271666439
Change-Id: I5a25e6cd4c41f32d1fb98ecfe43d67fa3a003187

google/quiche,google/quiche,google/quiche,google/quiche