Examine source code of Ctrly.co

{
  "name": "Ctrly.co",
  "description": "Inserting your signature is as easy as pressing Ctrl + Y",
  "version": "1.2.2",
  "manifest_version": 2,
  "icons": {
    "16": "/images/logo16.png",
    "32": "/images/logo32.png",
    "48": "/images/logo48.png",
    "128": "/images/logo128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "<all_urls>",
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "hello@alexandre.ehrlich.com",
      "strict_min_version": "42.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "jquery.min.js",
        "content.js"
      ]
    }
  ]
}