I don't think we should have first_event_time and last_event_time in LatencyInfo::LatencyComponent. From what I see in most cases, we log one event per component, so usually event_time, first_event_time, and last_event_time are all equal. LatencyInfo is sent cross-process as part of compositor frames and also in some other contexts. There's multiple components in each LatencyInfo, and there could be multiple LatencyInfo objects sent as part of a single compositor frame, so this is hundreds of bytes of cross-IPC data, which doesn't seem to be warranted. 

In cases where we need sub-component granularity for events (I am not sure if there are cases like that), can we just create separate components?

tdresser@, jbauman@, sadrul@ - WDYT?