Examine source code of Top 10 Domains

{
  "manifest_version": 2,
  "name": "Top 10 Domains",
  "version": "1.0",
  "description": "Lists the top 10 most visited domains in your browsing history.",
  "icons": {
    "48": "icons/logo.png"
  },
  "browser_action": {
    "default_icon": "icons/logo.png",
    "default_popup": "popup.html",
    "default_title": "Top 10 Domains"
  },
  "permissions": [
    "history",
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{fe17c455-26fb-49b2-9891-ca466e2bc5fc}"
    }
  }
}