Examine source code of JavaScript QR Code

{
  "manifest_version": 2,
  "name": "JavaScript QR Code",
  "short_name": "JavaScript QR Code generator",
  "description": "Make QR Codes in JavaScript",
  "version": "1.6.1",
  "icons": {
    "16": "assets/icon_16.png",
    "128": "assets/icon_128.png"
  },
  "applications": {
    "gecko": {
      "id": "@javascriptqrcode",
      "strict_min_version": "58.0"
    }
  },
  "permissions": [
    "tabs",
    "activeTab",
    "<all_urls>",
    "contextMenus"
  ],
  "browser_action": {
    "default_icon": {
      "19": "assets/icon_16.png",
      "38": "assets/icon_128.png"
    }
  },
  "content_security_policy": "script-src 'self'; default-src 'self'; img-src * data:; style-src 'self';",
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}