Examine source code of FBlock

{
  "applications": {
    "gecko": {
      "id": "fblock-rupertdev@outlook.com"
    }
  },
  "manifest_version": 2,
  "name": "FBlock",
  "version": "1.1resigned1",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Settings",
    "default_icon": {
      "32": "icons/32.png"
    }
  },
  "description": "Simply block sites based on a blacklist.",
  "options_ui": {
    "page": "config/config.html"
  },
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "block.js"
      ]
    }
  ]
}