Examine source code of Reader Mode

{
  "applications": {
    "gecko": {
      "strict_min_version": "58.0a1",
      "id": "{e1d879e7-a32d-41ec-9c7e-dd43f04dd086}"
    }
  },
  "browser_action": {
    "browser_style": true,
    "default_title": "Reader Mode",
    "default_icon": {
      "64": "icons/logo_64.png"
    },
    "default_popup": "tabs.html"
  },
  "description": "Change the currently opened tab to reader mode if available.",
  "homepage_url": "https://github.com/nabendu82/Reader-Mode",
  "manifest_version": 2,
  "name": "Reader Mode",
  "permissions": [
    "tabs"
  ],
  "version": "1.1resigned1",
  "icons": {
    "32": "icons/logo_32.png",
    "48": "icons/logo_48.png",
    "64": "icons/logo_64.png"
  }
}