Examine source code of Classic Layout for Reddit

{
  "manifest_version": 3,
  "name": "Classic Layout for Reddit",
  "version": "3.11.3",
  "description": "Rebuilds Reddit into old Reddit's classic UI from its API: infinite scroll, keyboard nav, collapse, night mode, filters.",
  "browser_specific_settings": {
    "gecko": {
      "id": "old-reddit-redirect@extension.local",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "*://reddit.com/*",
    "*://*.reddit.com/*",
    "*://v.redd.it/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://www.reddit.com/*",
        "*://reddit.com/*",
        "*://new.reddit.com/*",
        "*://np.reddit.com/*",
        "*://amp.reddit.com/*",
        "*://sh.reddit.com/*"
      ],
      "js": [
        "common.js",
        "rebuild.js"
      ],
      "run_at": "document_start",
      "all_frames": false
    },
    {
      "matches": [
        "*://old.reddit.com/*",
        "*://i.reddit.com/*"
      ],
      "js": [
        "redirect.js"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "vendor/oldreddit.bundled.css"
      ],
      "matches": [
        "*://*.reddit.com/*"
      ]
    }
  ],
  "action": {
    "default_title": "Classic Layout for Reddit",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  }
}