Examine source code of Tinker for Twitch

{
  "manifest_version": 2,
  "name": "Tinker for Twitch",
  "short_name": "Tinker",
  "version": "2.5.4",
  "description": "Control visual elements of Twitch.tv",
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "css": [
        "override.css"
      ],
      "js": [
        "chromestorageservice.js",
        "override.js"
      ],
      "matches": [
        "https://www.twitch.tv/*"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "options.html"
  },
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  }
}