Examine source code of YouTube Audio Only

{
  "manifest_version": 2,
  "name": "YouTube Audio Only",
  "version": "1.0.0",
  "description": "Turns YouTube into an audio-only experience by blocking video streams and hiding visual playback.",
  "permissions": [
    "storage",
    "tabs",
    "webRequest",
    "webRequestBlocking",
    "*://*.googlevideo.com/*",
    "*://*.youtube.com/*",
    "*://youtube.com/*",
    "*://m.youtube.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "id": "{3a35b6a9-5cf6-4592-9a95-e299e0a036a5}"
    }
  },
  "browser_action": {
    "default_title": "YouTube Audio Only",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*",
        "*://youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ]
}