Examine source code of Wheeltab

{
  "manifest_version": 2,
  "name": "Wheeltab",
  "version": "0.0.3",
  "default_locale": "en",
  "description": "__MSG_extension_description__",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "author": "Matthieu Corageoud",
  "applications": {
    "gecko": {
      "id": "wheeltab@matco.name",
      "strict_min_version": "45.0"
    }
  },
  "permissions": [
    "tabs",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background-script.js"
    ]
  }
}