Examine source code of PopupButton57

{
  "manifest_version": 2,
  "name": "PopupButton57",
  "version": "0.0.4",
  "description": "Turn popups on/off by clicking a button",
  "icons": {
    "48": "data/icon-48.png",
    "96": "data/icon-96.png"
  },
  "permissions": [
    "browserSettings"
  ],
  "browser_action": {
    "default_icon": {
      "16": "data/icon-16.png",
      "32": "data/icon-32.png",
      "64": "data/icon-64.png"
    },
    "default_title": "Turn Popups on/off"
  },
  "background": {
    "scripts": [
      "index.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{78f2fc3c-4b59-497d-a0fd-7a3fecd56c85}"
    }
  }
}