Examine source code of Tab Screenshot Button

{
  "manifest_version": 2,
  "name": "Tab Screenshot Button",
  "version": "1.0",
  "description": "Adds a browser button to capture a screenshot of the current tab.",
  "icons": {
    "64": "icons/icon64.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/icon64.png",
    "default_title": "Capture Tab Screenshot"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "18e5fb71-bdde-4390-9caf-c16fe62c0d8c@tab-screenshot-button",
      "strict_min_version": "78.0"
    }
  }
}