code: function AsyncSlice(category, title, colorId, start, args, duration,
                        opt_isTopLevel, opt_cpuStart, opt_cpuDuration,
                        opt_argsStripped) {
      tr.model.TimedEvent.call(this, start);
  
      this.category = category || '';
      // We keep the original title from the trace file in originalTitle since
      // some sub-classes, e.g. NetAsyncSlice, change the title field.
      this.originalTitle = title;
      this.title = title;
      this.colorId = colorId;
      this.args = args;
      this.startStackFrame = undefined;
      this.endStackFrame = undefined;
      this.didNotFinish = false;
      this.important = false;
      this.subSlices = [];
      this.parentContainer = undefined;
  
      this.id = undefined;
      this.startThread = undefined;
      this.endThread = undefined;
      this.cpuStart = undefined;
      this.cpuDuration = undefined;
      this.argsStripped = false;
  
      this.startStackFrame = undefined;
      this.endStackFrame = undefined;
  
      this.duration = duration;
  
  
      // TODO(nduca): Forgive me for what I must do.
      this.isTopLevel = (opt_isTopLevel === true);
  
      if (opt_cpuStart !== undefined)
        this.cpuStart = opt_cpuStart;
  
      if (opt_cpuDuration !== undefined)
        this.cpuDuration = opt_cpuDuration;
  
      if (opt_argsStripped !== undefined)
        this.argsStripped = opt_argsStripped;
    }
docs: A AsyncSlice represents an interval of time during which an
  asynchronous operation is in progress. An AsyncSlice consumes no CPU time
  itself and so is only associated with Threads at its start and end point.
  
  @constructor