def bytes(resource_type)
      @events.select {|e|
        e.is_a?(ResponseReceived) && e.resource_type == resource_type
      }.map { |e|
        e.request_id
      }.map { |request_id|
        data_received_for_request(request_id)
      }.flatten.inject(0) { |bytes_sum, n| bytes_sum + n.data_length }
    end
def bytes(resource_type)
      @events.select {|e|
        e.is_a?(ResponseReceived) && e.resource_type == resource_type
      }.map { |e|
        e.request_id
      }.map { |request_id|
        data_received_for_request(request_id)
      }.flatten.inject(0) { |bytes_sum, n| bytes_sum + n.data_length }
    end
The number of bytes downloaded for a particular resource type. If the
 resource was gzipped during transfer then the uncompressed size is
 reported.

 The HTTP headers for the response are NOT included in the byte count.

 Possible resource types: 'Document','Script', 'Image', 'Stylesheet',
 'Other'.