Examine source code of HoverCom

{
  "name": "HoverCom",
  "version": "0.9.4",
  "manifest_version": 2,
  "default_locale": "en",
  "applications": {
    "gecko": {
      "id": "we@leaveur.com"
    }
  },
  "browser_action": {
    "browser_style": false,
    "default_title": "HoverCom",
    "default_popup": "content/popup.html",
    "default_icon": {
      "32": "icons/luc.png"
    }
  },
  "background": {
    "page": "content/background.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content/content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "<all_urls>",
    "activeTab",
    "tabs",
    "storage"
  ]
}