Examine source code of cool-clock

{
  "manifest_version": 2,
  "name": "clock",
  "description": "it s a clock",
  "version": "1.0.1",
  "icons": {
    "64": "icons/icon.png"
  },
  "permissions": [
    "storage"
  ],
  "background": {
    "scripts": [
      "background_script.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.mozilla.org/*"
      ],
      "js": [
        "content_script.js"
      ]
    }
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "browser_action": {
    "default_icon": {
      "64": "icons/icon.png"
    },
    "default_popup": "browserAction/index.html",
    "default_title": "clock"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{3ba48b5a-07ed-4332-a3ff-f1c5fd83b103}"
    }
  }
}