Examine source code of Preposition Trainer

{
  "manifest_version": 2,
  "name": "Preposition Trainer",
  "version": "1.0",
  "description": "Help you choose the correct preposition.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1536db8f-d75f-47d3-8e12-bfde267e2e4b}"
    }
  }
}