Examine source code of CleanTabs

{
  "manifest_version": 2,
  "name": "CleanTabs",
  "version": "1.2",
  "description": "Unload inactive tabs to free up memory",
  "browser_specific_settings": {
    "gecko": {
      "id": "cleantabs@matthiashuebner.at"
    }
  },
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    },
    "default_title": "Clean Tabs",
    "default_popup": "popup/popup.html"
  },
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  }
}