Examine source code of New tab in Reader View

{
  "manifest_version": 2,
  "name": "New tab in Reader View",
  "version": "1.4",
  "description": "Opens current page in reader view mode",
  "homepage_url": "https://github.com/sigsergv/ff-open-reader-view",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "background": {
    "scripts": [
      "open-rv.js"
    ]
  },
  "permissions": [
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "Reader View It!"
  },
  "applications": {
    "gecko": {
      "id": "0d008388-6e3f-417d-9703-146f14f83642@regolit.com"
    }
  }
}