Examine source code of Address Bar Splash

{
  "manifest_version": 2,
  "name": "Address Bar Splash (Page Load Effect)",
  "version": "1.0",
  "description": "Show a small splash/ripple effect near the top of the page when a page begins loading (visual hint near the address bar).",
  "permissions": [
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "style.css"
      ],
      "run_at": "document_start"
    }
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{059b704b-a861-42fc-a703-174fcca9350b}"
    }
  }
}