Examine source code of Fast-forward merge for GitHub

{
  "manifest_version": 3,
  "name": "Fast-forward merge for GitHub",
  "description": "Shows whether a GitHub pull request or branch can be fast-forward merged.",
  "version": "0.1.5",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "host_permissions": [
    "https://api.github.com/*"
  ],
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "ff-for-github@hyeon.me",
      "strict_min_version": "127.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "open_in_tab": false,
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://github.com/*"
      ],
      "exclude_matches": [
        "https://github.com/login*",
        "https://github.com/session*"
      ],
      "run_at": "document_idle",
      "css": [
        "content-scripts/content.css"
      ],
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}