function destroy (parentWindow) {
  // destroy all under this window
  for (let tab of tabManager.getAll(parentWindow)) {
    if (tab.id in views) {
      views[tab.id].webContents.destroy()
      delete views[tab.id]
    }
  }
}
Perm Prompt

NOTES
- Perm Prompt views are created as-needed, and desroyed when not in use
- Perm Prompt views are attached to individual BrowserView instances
- Perm Prompt views are shown and hidden based on whether its owning BrowserView is visible