Examine source code of Music Re-Tuner

{
  "manifest_version": 3,
  "name": "__MSG_appName__",
  "version": "2.0.19",
  "description": "__MSG_appDescription__",
  "default_locale": "en",
  "browser_specific_settings": {
    "gecko": {
      "id": "yt-music-retuner@musicretuner.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "permissions": [
    "activeTab",
    "storage",
    "tabs"
  ],
  "host_permissions": [
    "https://*.youtube.com/*",
    "https://music.apple.com/*",
    "https://*.spotify.com/*",
    "https://license.musicretuner.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon-16.png",
      "48": "icon-48.png",
      "128": "icon-128.png"
    }
  },
  "icons": {
    "16": "icon-16.png",
    "32": "icon-32.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.youtube.com/*"
      ],
      "js": [
        "content_youtube.js"
      ]
    },
    {
      "matches": [
        "https://music.apple.com/*"
      ],
      "js": [
        "content_apple.js"
      ]
    },
    {
      "matches": [
        "https://*.spotify.com/*"
      ],
      "all_frames": true,
      "run_at": "document_start",
      "js": [
        "content_spotify.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "retuner-worklet.js",
        "spotify-page-engine.js"
      ],
      "matches": [
        "https://*.youtube.com/*",
        "https://music.apple.com/*",
        "https://*.spotify.com/*"
      ]
    }
  ]
}