Examine source code of Farm Heroes

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#b4e4f7",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Farm Heroes",
  "manifest_version": 2,
  "description": "<a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/3b6002aabbbc868494c7f75c4dd6818fcc1176a45d94844a155add8c19aae2c3/https%3A//king.com/games\">https://king.com/games</a>"
}