Examine source code of Ping Checker

{
  "manifest_version": 2,
  "name": "Ping Checker",
  "version": "0.9",
  "description": "Displays the current ping in the icon space",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_action": {
    "default_icon": "icon48.png",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab",
    "*://*/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{dff53666-48ad-43fc-a56e-f32b6b265c3c}"
    }
  }
}