event.Log removed
event.Print -> event.Log
event.Record -> event.Metric
event.StartSpan -> event.Start
In order to support this core now exposes the MakeEvent and Export functions.
Change-Id: Ic7550d88dbf400e32c419adbb61d1546c471841e
Reviewed-on: https://go-review.googlesource.com/c/tools/+/229238
Reviewed-by: Robert Findley <rfindley@google.com>
