Examine source code of Twitter Image Downloader

{
  "manifest_version": 2,
  "name": "Twitter Image Downloader",
  "short_name": "TwiImgDLer",
  "version": "2.2.1",
  "description": "Download and rename original image in twitter timeline",
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "background": {
    "scripts": [
      "dist/background.bundle.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "https://twitter.com/*",
        "https://tweetdeck.twitter.com/*"
      ],
      "js": [
        "dist/content.bundle.js"
      ]
    }
  ],
  "options_ui": {
    "page": "dist/options.html",
    "chrome_style": false
  },
  "permissions": [
    "tabs",
    "contextMenus",
    "downloads",
    "storage",
    "https://twitter.com/*",
    "https://tweetdeck.twitter.com/*"
  ]
}