Examine source code of Stop It Grandpa

{
  "manifest_version": 2,
  "name": "Stop It Grandpa",
  "version": "1.1.0",
  "description": "Prevents grandpa from lookin' at his favorite propaganda.",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "converted_from_user_script": true,
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "<all_urls>",
    "webRequest",
    "webRequestBlocking",
    "tabs"
  ]
}