Examine source code of uBookmark

{
  "name": "uBookmark",
  "description": "Universal Bookmark Manager",
  "version": "2.1resigned1",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "icons/16px.png",
    "128": "icons/128px.png"
  },
  "browser_action": {
    "default_icon": "icons/128px.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "permissions": [
    "tabs"
  ],
  "manifest_version": 2,
  "content_security_policy": "script-src 'self' ; object-src 'self'",
  "browser_specific_settings": {
    "gecko": {
      "id": "{f723a648-3b7e-45f3-87e0-02b51d8e590a}"
    }
  }
}