Examine source code of Trending Now

{
  "manifest_version": 2,
  "name": "Trending Now",
  "version": "1.1",
  "description": "Display trending keywords fetched from trend.aogobo.com directly inside the toolbar popup.",
  "icons": {
    "16": "icon-16.png",
    "32": "icon-32.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icon-16.png",
      "32": "icon-32.png",
      "48": "icon-48.png"
    },
    "default_title": "Trending Now",
    "default_popup": "popup.html"
  },
  "permissions": [
    "https://trend.aogobo.com/*",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{16f92d66-eeca-4d49-9ff4-b067be7189bc}"
    }
  }
}