Examine source code of Time Machine

{
  "manifest_version": 2,
  "name": "Time Machine",
  "version": "1.5",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "tabs",
    "activeTab",
    "scripting"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "3389143.png",
      "48": "3389143.png",
      "128": "3389143.png"
    }
  },
  "options_page": "options.html",
  "browser_specific_settings": {
    "gecko": {
      "id": "{38c8cd46-e3e9-4a91-8636-1e176f5a47ed}"
    }
  }
}