Examine source code of Twitter Customiser

{
  "name": "Twitter Customiser",
  "description": "Customise what metrics and content appears in the Media tabs, List tabs and more when browsing Twitter!",
  "version": "1.5",
  "manifest_version": 2,
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_icon": "/images/herecomeskingskeletor128.png",
    "default_title": "Twitter Customiser",
    "default_popup": "popup.html"
  },
  "icons": {
    "128": "/images/herecomeskingskeletor128.png"
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "content_scripts": [
    {
      "js": [
        "jquery.min.js",
        "mainscript.js"
      ],
      "matches": [
        "http://twitter.com/*",
        "https://twitter.com/*"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{8ed9f59f-fbeb-431c-a157-27553a0c8588}"
    }
  }
}