Examine source code of FlashTabs

{
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "FlashTabs"
  },
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "content_security_policy": "script-src 'self' https://flashtabs.co; object-src 'self'",
  "description": "FlashTabs is a digital flashcard app in your new tab screen. Create decks, add some cards, then learn every time you open a new tab.",
  "homepage_url": "https://flashtabs.co/",
  "icons": {
    "16": "img/brand_16x16.png",
    "32": "img/brand_32x32.png",
    "48": "img/brand_48x48.png",
    "128": "img/brand_128x128.png"
  },
  "manifest_version": 2,
  "name": "FlashTabs",
  "permissions": [],
  "short_name": "FlashTabs",
  "version": "2.0.1"
}