Examine source code of GOOGLE SIGNOUT

{
  "manifest_version": 2,
  "name": "GOOGLE SIGNOUT",
  "description": "This will sign out all google accounts from the browser",
  "homepage_url": "https://accounts.google.com/Logout?hl=en",
  "version": "1.1resigned1",
  "icons": {
    "32": "icons/page-32.png",
    "48": "icons/page-48.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "19": "icons/page-19.png",
      "38": "icons/page-38.png"
    },
    "default_title": "sign out all google accounts from the browser"
  },
  "permissions": [
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{07bc98d7-d8e6-4dca-b4fe-d68965efb477}"
    }
  }
}