Examine source code of MissionChief Enhancer

{
  "manifest_version": 2,
  "name": "MissionChief Enhancer",
  "version": "1.0",
  "description": "Shows you needed vehicles.",
  "icons": {
    "48": "icons/icon.png"
  },
  "permissions": [
    "activeTab",
    "<all_urls>"
  ],
  "sidebar_action": {
    "default_title": "MissionChief Enhancer",
    "default_panel": "sidebar.html",
    "default_icon": {
      "48": "icons/icon.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{c302b629-c221-436b-a906-dea8781adf17}"
    }
  }
}