Examine source code of Pixel Drawing Extension

{
  "manifest_version": 2,
  "name": "Pixel Drawing Extension",
  "version": "1.0",
  "description": "Draw with pixels in a popup window",
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a0e6ec48-2a32-4429-8cca-8381fe9affb1}"
    }
  }
}