Examine source code of MrNiceGuy

{
  "manifest_version": 2,
  "name": "MrNiceGuy",
  "description": "Replaces bad words with nice words",
  "homepage_url": "https://github.com/mdn/webextensions-examples/tree/master/emoji-substitution",
  "version": "0.9resigned1",
  "icons": {
    "48": "icons/LogoChild.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "./emojiMap.js",
        "./substitute.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{2124f63d-d4e3-46bf-b32a-5bbd41c9fe0d}"
    }
  }
}