Summary:
To avoid plugins to collect data forever and store it (if they are never opened), introduced a hard-coded default limit on how many events will be preserved.
A semantic change is that plugins have to be potentially resistant against missing events. So far, during testing, this didn't seem to cause any problems.
Reviewed By: jonathoma
Differential Revision: D19175912
fbshipit-source-id: 828be941e76b7356c9f5be7e5a49de9a7a31b0d2
0494a84d98