atom/packages/dev-live-reload/lib/base-theme-watcher.js

const fs = require('fs-plus')
const path = require('path')
const Watcher = require('./watcher')

module.exports = class BaseThemeWatcher extends Watcher {
  constructor () {
    super()
    this.stylesheetsPath = path.dirname(
      atom.themes.resolveStylesheet('../static/atom.less')
    )
    this.watch()
  }

  watch () {
    const filePaths = fs
      .readdirSync(this.stylesheetsPath)
      .filter(filePath => path.extname(filePath).includes('less'))

    for (const filePath of filePaths) {
      this.watchFile(path.join(this.stylesheetsPath, filePath))
    }
  }

  loadStylesheet () {
    this.loadAllStylesheets()
  }

  loadAllStylesheets () {
    atom.themes.reloadBaseStylesheets()
  }
}