Examine source code of Feruchemy

{
  "manifest_version": 2,
  "name": "Feruchemy",
  "version": "1.2.0",
  "description": "Save the page contents with type to the Coppermind.",
  "icons": {
    "48": "icons/1x/twotone_save_black_48dp.png",
    "96": "icons/2x/twotone_save_black_48dp.png"
  },
  "permissions": [
    "*://coppermind.herokuapp.com/*",
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/2x/twotone_save_black_48dp.png",
    "default_title": "Tag 'n Save",
    "default_popup": "popup/choose_type.html"
  }
}