message: Remove no longer used HeaderController
  Change-type: patch
diff: @@ -40,7 +40,6 @@ const settings = require('./models/settings')
  const windowProgress = require('./os/window-progress')
  const analytics = require('./modules/analytics')
  const availableDrives = require('./models/available-drives')
  -const selectionState = require('./models/selection-state')
  const driveScanner = require('./modules/drive-scanner')
  const osDialog = require('./os/dialog')
  const exceptionReporter = require('./modules/exception-reporter')
  @@ -411,40 +410,6 @@ app.config(($locationProvider) => {
  })
  })
  -app.controller('HeaderController', function (OSOpenExternalService) {
  - /**
  - * @summary Open help page
  - * @function
  - * @public
  - *
  - * @description
  - * This application will open either the image's support url, declared
  - * in the archive `manifest.json`, or the default Etcher help page.
  - *
  - * @example
  - * HeaderController.openHelpPage();
  - */
  - this.openHelpPage = () => {
  - const DEFAULT_SUPPORT_URL = 'https://github.com/balena-io/etcher/blob/master/SUPPORT.md'
  - const supportUrl = selectionState.getImageSupportUrl() || DEFAULT_SUPPORT_URL
  - OSOpenExternalService.open(supportUrl)
  - }
  -
  - /**
  - * @summary Whether to show the help link
  - * @function
  - * @public
  - *
  - * @returns {Boolean}
  - *
  - * @example
  - * HeaderController.shouldShowHelp()
  - */
  - this.shouldShowHelp = () => {
  - return !settings.get('disableExternalLinks')
  - }
  -})
  -
  app.controller('StateController', function ($rootScope, $scope) {
  const unregisterStateChange = $rootScope.$on('$stateChangeSuccess', (event, toState, toParams, fromState) => {
  this.previousName = fromState.name
  