Examine source code of Emoji Catcher

{
  "manifest_version": 2,
  "name": "Emoji Catcher",
  "version": "1.0",
  "description": "Catch falling emojis in a light canvas game inside the popup. Use arrow keys to move the basket.",
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_title": "Emoji Catcher",
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{cf867741-7a99-445b-8b21-350ad596f41b}"
    }
  }
}