Examine source code of Overture

{
  "manifest_version": 2,
  "name": "Overture",
  "version": "1.0",
  "description": "Overture - new tab page.",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "developer": {
    "name": "Pratilectron",
    "url": "https://github.com/Pratilectron"
  },
  "chrome_settings_overrides": {},
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "omnibox": {
    "keyword": "newtab"
  },
  "permissions": [
    "browserSettings",
    "tabs"
  ]
}