Examine source code of imageSearchTool

{
  "name": "imageSearch",
  "version": "1.1",
  "manifest_version": 2,
  "description": "ImageSearchTool",
  "icons": {
    "16": "image/search_16.png",
    "48": "image/search_48.png",
    "128": "image/search_128.png"
  },
  "background": {
    "scripts": [
      "browser-polyfill.min.js",
      "background.js"
    ],
    "persistent": true
  },
  "permissions": [
    "contextMenus",
    "tabs",
    "activeTab",
    "webRequest",
    "webRequestBlocking",
    "http://*/*",
    "https://*/*",
    "webNavigation"
  ]
}