Examine source code of FirePHP

{
  "manifest_version": 2,
  "description": "Log from PHP to a devtools panel.",
  "name": "FirePHP (Official)",
  "version": "1.5.7",
  "short_name": "FirePHP",
  "homepage_url": "http://firephp.org",
  "author": "Christoph Dorn",
  "icons": {
    "16": "skin/__icon_16.png",
    "48": "skin/__icon_48.png",
    "128": "skin/__icon_128.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "webNavigation",
    "webRequest",
    "webRequestBlocking",
    "http://*/",
    "https://*/"
  ],
  "content_security_policy": "script-src 'self'; style-src 'self'; object-src 'self'; img-src 'self'",
  "applications": {
    "gecko": {
      "id": "FirePHPExtension-Build@firephp.org",
      "strict_min_version": "56.0"
    }
  },
  "devtools_page": "devtools-page.html",
  "background": {
    "page": "background.html"
  },
  "page_action": {
    "default_popup": "scripts/devtools/dist/page-action.html",
    "default_icon": {
      "16": "skin/__icon_16.png",
      "48": "skin/__icon_48.png",
      "128": "skin/__icon_128.png"
    }
  },
  "version_name": "1.5.7"
}