Examine source code of DoppelBangers

{
  "manifest_version": 2,
  "name": "DoppelBangers",
  "version": "1.0.2resigned1",
  "applications": {
    "gecko": {
      "id": "@extension-doppelbangers003",
      "strict_min_version": "42.0"
    }
  },
  "permissions": [
    "activeTab",
    "contextMenus"
  ],
  "description": "Reverse Image Search",
  "background": {
    "scripts": [
      "index.js"
    ]
  },
  "icons": {
    "48": "icon48.png",
    "96": "icon96.png"
  }
}