Examine source code of 2ManyTabs

{
  "manifest_version": 2,
  "name": "2ManyTabs",
  "description": "Replace default new tab page in Chrome with a useful new tab page.",
  "version": "0.2",
  "chrome_url_overrides": {
    "newtab": "tab.html"
  },
  "icons": {
    "128": "128.png"
  },
  "permissions": [
    "bookmarks"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{47c8b571-b102-4dcd-9f0f-8498bdadc724}"
    }
  }
}