Examine source code of Block iFrames

{
  "author": "igorlogius",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "200": "icon.png"
  },
  "browser_action": {},
  "description": "",
  "manifest_version": 2,
  "name": "Block iFrames",
  "permissions": [
    "<all_urls>",
    "webRequest",
    "webRequestBlocking"
  ],
  "version": "1.1.3",
  "browser_specific_settings": {
    "gecko": {
      "id": "{17585bf9-2b7f-41b9-8113-6f0709375536}"
    }
  }
}