Examine source code of HideRT - Hide retweets

{
  "manifest_version": 2,
  "name": "HideRT",
  "description": "Show and hide retweets from Twitter timeline.",
  "version": "1.1",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png"
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png"
    },
    "default_title": "Hide retweets"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.twitter.com/*"
      ],
      "js": [
        "hidert.js"
      ],
      "css": [
        "hidert.css"
      ]
    }
  ]
}