Examine source code of Simple Popup Add-on

{
  "manifest_version": 2,
  "name": "Simple Popup Add-on",
  "version": "1.0",
  "description": "A simple Mozilla Firefox add-on that shows a popup.",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_popup": "popup.html",
    "default_title": "Show Popup!"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "popup.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{464eca3b-0166-4acc-a0c9-2f302bff98dd}"
    }
  }
}