Examine source code of Top Site Recommender

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "description": "__MSG_extensionDescription__",
  "icons": {
    "32": "icons/logo_32.png",
    "64": "icons/logo_64.png",
    "128": "icons/logo_128.png"
  },
  "version": "1.0",
  "chrome_url_overrides": {
    "newtab": "sites.html"
  },
  "permissions": [
    "topSites"
  ],
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "54.0a1",
      "id": "{8038aaae-2adf-4b0e-a05a-4fc88598698d}"
    }
  }
}