Examine source code of Browser Media Controls

{
  "manifest_version": 3,
  "name": "Browser Media Controls",
  "version": "2.5.1",
  "description": "Connect browser media to the Browser Media Controls Windows app and Stream Deck integration.",
  "permissions": [
    "tabs",
    "scripting",
    "nativeMessaging",
    "storage"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "icons": {
    "16": "imgs/icon16.png",
    "32": "imgs/icon32.png",
    "48": "imgs/icon48.png",
    "128": "imgs/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_security_policy": {
    "extension_pages": "script-src 'self'; connect-src ws://127.0.0.1:21213 ws://127.0.0.1:21214 ws://127.0.0.1:21215 ws://127.0.0.1:21216 ws://127.0.0.1:21217 ws://127.0.0.1:21218 ws://127.0.0.1:21219 ws://127.0.0.1:21221 ws://*:21225 ws://*:21226;"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "browser-media-controls@qaem.local",
      "strict_min_version": "128.0"
    }
  },
  "action": {
    "default_title": "Browser Media Controls",
    "default_popup": "options.html",
    "default_icon": {
      "16": "imgs/action16.png",
      "32": "imgs/action32.png",
      "48": "imgs/action48.png",
      "128": "imgs/action128.png"
    }
  },
  "options_ui": {
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "exclude_matches": [
        "http://localhost/*",
        "http://127.0.0.1/*"
      ],
      "js": [
        "content-script.js"
      ],
      "run_at": "document_idle"
    }
  ]
}