Examine source code of Rotate that Video Player

{
  "manifest_version": 3,
  "short_name": "RtVP",
  "homepage_url": "https://www.stefanvd.net/support/",
  "description": "__MSG_description__",
  "author": "Stefan vd",
  "icons": {
    "16": "images/icon16.png",
    "24": "images/icon24.png",
    "32": "images/icon32.png",
    "48": "images/icon48.png",
    "96": "images/icon96.png",
    "128": "images/icon128.png"
  },
  "action": {
    "default_title": "__MSG_name__",
    "default_icon": {
      "16": "images/icon16.png",
      "19": "images/iconstick19.png",
      "20": "images/iconstick20.png",
      "32": "images/icon32.png",
      "38": "images/iconstick38.png",
      "40": "images/iconstick40.png",
      "64": "images/iconstick64.png"
    },
    "default_popup": "popup.html",
    "theme_icons": [
      {
        "light": "images/whiteicon16.png",
        "dark": "images/icon16.png",
        "size": 16
      },
      {
        "light": "images/whiteicon32.png",
        "dark": "images/icon32.png",
        "size": 32
      }
    ]
  },
  "default_locale": "en",
  "content_security_policy": {
    "extension_pages": "default-src 'none'; style-src 'self' 'unsafe-inline'; media-src https://www.stefanvd.net; frame-src https://www.youtube.com https://www.stefanvd.net; connect-src https://www.stefanvd.net; script-src 'self'; img-src 'self' https://www.stefanvd.net * data:; object-src 'none'"
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "scripts/constants.js",
        "scripts/content.js",
        "scripts/rotate.js"
      ],
      "run_at": "document_end"
    }
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "version": "1.0.10",
  "name": "__MSG_name__",
  "background": {
    "scripts": [
      "scripts/constants.js",
      "scripts/background.js"
    ]
  },
  "commands": {
    "toggle-feature-rotateclockwise": {
      "suggested_key": {
        "default": "Ctrl+Shift+1",
        "mac": "MacCtrl+Shift+1"
      },
      "description": "__MSG_titlerotateclockwise__"
    },
    "toggle-feature-rotatecounter": {
      "suggested_key": {
        "default": "Ctrl+Shift+2",
        "mac": "MacCtrl+Shift+2"
      },
      "description": "__MSG_titlerotatecounter__"
    },
    "toggle-feature-rotatereset": {
      "suggested_key": {
        "default": "Ctrl+Shift+3",
        "mac": "MacCtrl+Shift+3"
      },
      "description": "__MSG_titlerotatereset__"
    }
  },
  "permissions": [
    "activeTab",
    "scripting",
    "storage",
    "contextMenus"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "rotatethatvideoplayer@stefanvd.net",
      "strict_min_version": "113.0"
    }
  }
}