Examine source code of Friendly Github

{
  "name": "Friendly GitHub",
  "short_name": "FGH",
  "version": "18.9.13.2160resigned1",
  "description": "Makes GitHub a better Social Network",
  "homepage_url": "https://github.com/hermanya/friendly-github",
  "manifest_version": 2,
  "minimum_chrome_version": "58",
  "applications": {
    "gecko": {
      "id": "{073711a2-ea6d-49f2-98b6-0d7ea340c06f}",
      "strict_min_version": "55.0"
    }
  },
  "permissions": [
    "storage",
    "contextMenus",
    "activeTab",
    "https://api.github.com/*"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "options.html",
    "browser_style": true
  },
  "optional_permissions": [
    "http://*/*",
    "https://*/*"
  ],
  "icons": {
    "128": "icon.png"
  },
  "options_ui": {
    "chrome_style": true,
    "page": "options.html"
  },
  "background": {
    "scripts": [
      "browser-polyfill.min.js",
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "run_at": "document_start",
      "matches": [
        "https://github.com/*",
        "https://gist.github.com/*"
      ],
      "css": [
        "content.css"
      ],
      "js": [
        "browser-polyfill.min.js",
        "content.js"
      ]
    }
  ]
}