mergeAllLayers = hrService => {
  svgCanvas
    .getCurrentDrawing()
    .mergeAllLayers(historyRecordingService(hrService))
  svgCanvas.clearSelection()
  leaveContext()
  svgCanvas.changeSvgContent()
}
@function module:draw.mergeAllLayers
@param {module:history.HistoryRecordingService} hrService
@returns {void}