Examine source code of Dark Night Mode

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "version": "2.0.7",
  "name": "Dark Night Mode",
  "manifest_version": 2,
  "short_name": "darknightmode",
  "description": "It is a night mode for the entire Internet. It darkens all the websites you visit so that you can browse without straining your eyes",
  "permissions": [
    "tabs",
    "storage",
    "<all_urls>"
  ],
  "web_accessible_resources": [
    "css/*.css"
  ],
  "homepage_url": "https://darknightmode.com",
  "options_page": "templates/options.html",
  "offline_enabled": true,
  "icons": {
    "48": "icons/icon48.png",
    "128": "icons/icon.png"
  },
  "browser_action": {
    "default_icon": "icons/icon.png",
    "default_popup": "templates/popup.html"
  },
  "content_scripts": [
    {
      "all_frames": true,
      "match_about_blank": true,
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_start",
      "exclude_globs": [
        "*/chrome/newtab*"
      ],
      "js": [
        "js/main.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{27c3c9d8-95cd-44e6-ae9c-ff537348b9f3}"
    }
  }
}