Examine source code of Bandwidth Hero

{
  "manifest_version": 2,
  "name": "Bandwidth Hero - Live Image Compression",
  "short_name": "Bandwidth Hero",
  "description": "Saves data by compressing images on the page.",
  "version": "2.1.4",
  "icons": {
    "64": "assets/icon-128.png",
    "128": "assets/icon-256.png"
  },
  "browser_action": {
    "default_icon": "assets/icon-128.png",
    "default_title": "Bandwidth Hero",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "update.bundle.js",
      "background.bundle.js"
    ]
  },
  "permissions": [
    "activeTab",
    "tabs",
    "storage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ]
}