system_api: service_constants.h: add MetricsEvent

This adds constants for the MetricsEventService.
Ideally this would have gone in with the addition
of metrics_event.proto, but I had my chrome and cros
sources out of sync.

TEST=chromium compiles (cros clones these in Rust code)

Change-Id: I2407619196dd6fe75e3143caa932bb443ad5fffc
Commit-Ready: Luigi Semenzato <>
Tested-by: Luigi Semenzato <>
Reviewed-by: Dan Erat <>
1 file changed