Event is an event in the Chrome tracing format. The fields are mirrored exactly.
T represents the JSON object format in the Chrome tracing format. For more details, see: https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/preview
Decode decodes the JSON object format read from r into t. Call this with a t zero value.
Encode JSON encodes t into w.