function emitTraceTracker() {
    var now = wtf.now();
    var tracingScope = wtf.trace.enterTracingScope(now);

    var syncName = '$WTFTRACE:' + Math.floor(now * 1000);
    // TODO(benvanik): use timestamp instead
    consoleTime.call(goog.global.console, syncName);
    consoleTimeEnd.call(goog.global.console, syncName);

    wtf.trace.leaveScope(tracingScope);
  }
Toggles capture of chrome:tracing data.
@private