Examine source code of Sleep Web

{
  "manifest_version": 2,
  "name": "Sleep Web",
  "version": "1.0",
  "description": "Pause and unpause Firefox.",
  "permissions": [
    "activeTab",
    "tabs",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/pause.png",
    "default_title": "Sleep"
  },
  "icons": {
    "48": "icons/pause.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b1a10e5e-3409-4f43-8866-88d644320f9b}"
    }
  }
}