Examine source code of Copymoji

{
  "manifest_version": 2,
  "name": "Copymoji",
  "version": "1.0",
  "description": "Adds a button offering emojis to copy with one click",
  "icons": {
    "32": "icons/thumbs-up.svg"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/thumbs-up.svg",
    "default_title": "Copymoji",
    "default_popup": "popup/emojis.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{767e2cb1-2d52-4d2e-86fc-5b41ea32e510}"
    }
  }
}