Examine source code of 5-Second BrainFlash

{
  "manifest_version": 2,
  "name": "5-Second BrainFlash",
  "version": "1.0.0",
  "description": "Show an image or phrase for 5 seconds, then hide it and ask a quick memory question.",
  "permissions": [],
  "browser_action": {
    "default_title": "5-Second BrainFlash",
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "brainflash-5s@example.com",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}