Examine source code of SalesForce Link Grabber

{
  "manifest_version": 2,
  "name": "SalesForce Link Grabber",
  "version": "1.1",
  "description": "Opens SalesForce Links in Existing Tab",
  "permissions": [
    "webNavigation",
    "*://*.force.com/*",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7fa91da9-9433-4eaf-816e-07721587d29a}"
    }
  }
}