Examine source code of WhoRenderedThis

{
  "manifest_version": 2,
  "name": "WhoRenderedThis",
  "description": "Hover over any element on a React app to see which component rendered it.",
  "version": "0.2.0",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "permissions": [
    "activeTab",
    "scripting",
    "<all_urls>"
  ],
  "web_accessible_resources": [
    "react-main-world.js",
    "content-scripts/inspector.css"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1aa232e0-a767-46e0-87bf-506513f52eff}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action": {}
}