Examine source code of Font Changer

{
  "manifest_version": 2,
  "name": "Font Changer",
  "version": "1.0",
  "description": "Change the font of any webpage with a selection of popular fonts. Save preferences per site and reset to default with a neon-themed interface.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c837f68f-8b48-4c34-8cec-1557b6775a5a}"
    }
  }
}