Examine source code of Narrator

{
  "manifest_version": 2,
  "name": "Narrator",
  "description": "This extension will read aloud selected text",
  "version": "1.0",
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon.png",
    "128": "icon128.png"
  },
  "permissions": [
    "activeTab",
    "tabs"
  ]
}