Examine source code of Medium Declutter Tool

{
  "manifest_version": 2,
  "name": "Medium Declutter Tool",
  "description": "Hides all the premium content so that Medium's feed only shows available articles",
  "version": "0.1",
  "author": "Austin Regnery",
  "content_scripts": [
    {
      "matches": [
        "*://*.medium.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_icon": {
      "19": "images/mdt-19.png",
      "38": "images/mdt-38.png"
    }
  },
  "icons": {
    "16": "images/mdt-16.png",
    "48": "images/mdt-48.png",
    "128": "images/mdt-128.png"
  }
}