Examine source code of 500px save

{
  "manifest_version": 2,
  "name": "500px save",
  "version": "3.2",
  "description": "Enables right click for images on 500px' .",
  "icons": {
    "48": "icons/500px.jpg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://500px.com/*",
        "*://web.500px.com/*"
      ],
      "js": [
        "app.js"
      ]
    }
  ]
}