Examine source code of QRCode Web Extension

{
  "manifest_version": 2,
  "version": "0.0.3",
  "name": "QRCode Web Extension",
  "description": "Show QRCode with current URL.",
  "author": "ziguifrido",
  "browser_action": {
    "default_title": "QRCode Web Extension",
    "default_popup": "index.html",
    "default_icon": "icon.jpg"
  },
  "permissions": [
    "tabs"
  ],
  "icons": {
    "48": "icon.jpg"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "index.js"
      ]
    }
  ]
}