Examine source code of Reddit Gallery

{
  "manifest_version": 2,
  "name": "Reddit Gallery",
  "version": "0.4.7",
  "description": "Turns old reddit into an image gallery.",
  "permissions": [
    "*://old.reddit.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{fd1b33ac-2700-11ed-a261-0242ac120002}",
      "strict_min_version": "48.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://old.reddit.com/*"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "*://old.reddit.com/*"
      ],
      "js": [
        "scrapePostData.js",
        "onNewPosts.js",
        "createGalleryItem.js",
        "main.js"
      ],
      "run_at": "document_end"
    }
  ],
  "web_accessible_resources": [
    "default.png"
  ]
}