Examine source code of Personalized Backgrounds

{
  "manifest_version": 2,
  "name": "Personalized Backgrounds",
  "version": "1.0",
  "description": "Allow users to upload and set personalized backgrounds for their browser.",
  "permissions": [
    "storage",
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon.png"
  },
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{dc9d0d0b-19a6-4bfe-bc29-bdbfbc549b22}"
    }
  }
}