Examine source code of Blur Images

{
  "manifest_version": 2,
  "name": "Blur Images",
  "version": "1.1resigned1",
  "description": "Blur images and show up on mouve over",
  "icons": {
    "48": "icons/border-48.png"
  },
  "background": {
    "scripts": [
      "main.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://web.whatsapp.com/*"
      ],
      "css": [
        "blur-images.css"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "32": "icons/blur-icon.jpeg"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ddd5469e-6039-4f9a-aa93-63be8667ce75}"
    }
  }
}