Examine source code of ping

{
  "description": "Just a toolbar button that shows if a server is up or not.",
  "manifest_version": 2,
  "name": "ping",
  "version": "1.2.1resigned1",
  "homepage_url": "https://github.com/S2-/ping",
  "applications": {
    "gecko": {
      "id": "{46b66c4d-605f-4f4d-8689-20b44b45656d}"
    }
  },
  "icons": {
    "48": "icons/offline-48.png"
  },
  "browser_action": {
    "default_icon": "icons/offline-32.png",
    "theme_icons": [
      {
        "light": "icons/offline-32.png",
        "dark": "icons/offline-32.png",
        "size": 32
      }
    ],
    "default_title": "ping",
    "default_popup": "popup/ping.html"
  },
  "background": {
    "page": "background-page.html"
  },
  "permissions": [
    "storage",
    "<all_urls>",
    "webRequest",
    "notifications"
  ]
}