Examine source code of Volume Control Tabs

{
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "manifest_version": 2,
  "name": "Volume Control",
  "version": "2.7",
  "description": "Control the volume of each tab.",
  "browser_specific_settings": {
    "gecko": {
      "id": "volume@vzze"
    }
  },
  "icons": {
    "48": "icons/flowy.png"
  },
  "browser_action": {
    "default_icon": "icons/flowy.png",
    "default_title": "Volume",
    "default_area": "navbar",
    "browser_style": true,
    "default_popup": "popup.html"
  },
  "permissions": [
    "tabs",
    "<all_urls>",
    "storage"
  ]
}