Examine source code of Too Wide!

{
  "manifest_version": 2,
  "name": "Too Wide!",
  "version": "2.1.1",
  "icons": {
    "24": "/icons/icon-24.png",
    "48": "/icons/icon-48.png",
    "96": "/icons/icon-96.png"
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "storage"
  ],
  "options_ui": {
    "page": "/options/options.html"
  },
  "browser_action": {
    "default_icon": {
      "24": "/icons/icon-24.png",
      "48": "/icons/icon-48.png",
      "96": "/icons/icon-96.png"
    },
    "default_title": "Too Wide!",
    "default_popup": "popup/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "fix-width.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{15bfcf37-0027-4176-8293-efa0ee631f5d}"
    }
  }
}