Examine source code of E621 Helper

{
  "manifest_version": 2,
  "name": "E621 Helper",
  "version": "1.0",
  "permissions": [
    "activeTab"
  ],
  "description": "Your personal e621 Search Helper",
  "icons": {
    "48": "e6Helper.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://e621.net/*"
      ],
      "js": [
        "popup.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "48": "e6Helper.png"
    },
    "default_popup": "main.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ee857102-0db4-4449-a9ae-8e01507dca6c}"
    }
  }
}