Examine source code of PopupSound

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "description": "__MSG_extensionDescription__",
  "author": "Terry",
  "version": "0.3",
  "default_locale": "en",
  "offline_enabled": true,
  "icons": {
    "32": "icon_32.png",
    "96": "icon_96.png",
    "128": "icon_128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "webNavigation",
    "downloads"
  ]
}