Examine source code of Search Derussification

{
  "manifest_version": 2,
  "name": "Search DeRussification",
  "version": "1.2.1",
  "description": "Delete all russian sites from the Google Search.",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.google.com/*",
        "*://*.duckduckgo.com/*",
        "*://*.google.com.ua/*"
      ],
      "js": [
        "clean.js"
      ],
      "run_at": "document_end",
      "all_frames": true
    }
  ],
  "browser_action": {
    "browser_style": true,
    "default_icon": "icons/icon-48.png",
    "default_popup": "popup/index.html"
  },
  "permissions": [
    "storage",
    "*://*.github.com/*",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9aeed847-b515-4b3a-a37e-da617533b063}"
    }
  }
}