Examine source code of Blaseball+

{
  "manifest_version": 2,
  "author": "leo60228",
  "developer": {
    "name": "leo60228",
    "url": "https://leo60228.space"
  },
  "homepage_url": "https://github.com/leo60228/blaseball-plus",
  "name": "Blaseball+",
  "description": "Adds extra functionality to the Blaseball interface. Icon from game-icons.net.",
  "version": "1.13.1",
  "content_scripts": [
    {
      "matches": [
        "*://*.blaseball.com/*"
      ],
      "js": [
        "content_script.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background_script.js"
    ]
  },
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "*://*.blaseball.com/*",
    "https://d35iw2jmbg6ut8.cloudfront.net/*"
  ],
  "options_ui": {
    "browser_style": true,
    "page": "options_page.html"
  },
  "icons": {
    "48": "icon.png",
    "96": "icon@2x.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{bc4e0acf-acd5-4c45-b7af-699f6734d1ad}"
    }
  }
}