Examine source code of BTC Live Tracker

{
  "manifest_version": 2,
  "name": "BTC Live Tracker",
  "version": "1.0",
  "description": "Fast way to get btc price at the current time.",
  "icons": {
    "48": "icons/btc2.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/btc2.png",
    "default_title": "BTC Live Tracker",
    "default_popup": "index.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{26f4e169-19d6-4b0e-a88c-c2c6e447fb41}"
    }
  }
}