Examine source code of Browser Clock

{
  "name": "Browser Clock",
  "description": "Pop up windows clock",
  "manifest_version": 2,
  "version": "1.0.7resigned1",
  "permissions": [
    "tabs",
    "unlimitedStorage",
    "<all_urls>"
  ],
  "icons": {
    "19": "images/19.png",
    "48": "images/48.png",
    "128": "images/128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "19": "images/19.png",
      "38": "images/38.png"
    },
    "default_title": "Start Browser Clock"
  },
  "applications": {
    "gecko": {
      "id": "browserclock@codingdirectional.info",
      "strict_min_version": "42.0"
    }
  }
}