Examine source code of Shadowing Assistant

{
  "manifest_version": 2,
  "name": "Shadowing Assistant",
  "version": "1.0",
  "description": "Repeat sentences to practice pronunciation.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{fd40f21a-80e3-4e2b-b257-5ce6480a0541}"
    }
  }
}