Examine source code of Url image replacer

{
  "manifest_version": 2,
  "name": "Url image replacer",
  "version": "1.0",
  "description": "Allows override of image URLs at load time",
  "icons": {
    "48": "icons/48-beauty.png",
    "96": "icons/96-beauty.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "accounts.firefox.com.handball368@passmail.net",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action": {
    "default_icon": "icons/96-beauty.png",
    "default_title": "Url Image Replacer",
    "default_popup": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "replacer.js"
      ]
    }
  ],
  "permissions": [
    "<all_urls>",
    "storage"
  ]
}