Examine source code of Volume Balancer

{
  "manifest_version": 2,
  "name": "Volume Balancer",
  "version": "1.0",
  "description": "__MSG_description__",
  "default_locale": "en",
  "permissions": [
    "tabs",
    "webNavigation",
    "webRequest",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/icon64.png",
    "default_title": "__MSG_name__",
    "default_popup": "popup.html"
  },
  "icons": {
    "64": "icons/icon64.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "volumebalancer@version1",
      "strict_min_version": "68.0"
    }
  }
}