Examine source code of HoverTranslator

{
  "manifest_version": 2,
  "name": "HoverTranslator",
  "version": "0.13",
  "description": "Easy way to get on the fly translation of words / sentences by hovering on the text",
  "icons": {
    "48": "images/logo/ht-logo-48.png"
  },
  "permissions": [
    "*://translate.googleapis.com/*",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "ht.js"
      ],
      "css": [
        "/css/ht.css"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background/controller.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "64": "images/icons/page-64.png"
    },
    "default_title": "HoverTranslator",
    "default_popup": "popup/popup.html"
  }
}